The CIF_CORE dictionary records all the CORE data items defined and used with in the Crystallographic Information Framework (CIF).
Generated from /home/jrh/COMCIFS/cif_core/cif_core.dic, version 3.0.06
Categories that may have more than one row are called loop categories. Datanames making up the keys for these categories have a dot suffix.
CIF_CORE
The CIF_CORE group contains the definitions of data items that are common to all domains of crystallographic studies.
DIFFRACTION
The DICTIONARY group encompassing the CORE DIFFRACTION data items defined and used with in the Crystallographic Information Framework (CIF).
DIFFRN
The CATEGORY of data items used to describe the diffraction experiment.
_diffrn.ambient_environment
The gas or liquid environment of the crystal sample, if not air.
_diffrn.ambient_pressure
Mean hydrostatic pressure at which intensities were measured.
_diffrn.ambient_pressure_gt
Mean hydrostatic pressure above which intensities were measured. These items allow for a pressure range to be given. _diffrn.ambient_pressure should be used in preference to this item when possible.
_diffrn.ambient_pressure_lt
Mean hydrostatic pressure below which intensities were measured. These items allow for a pressure range to be given. _diffrn.ambient_pressure should be used in preference to this item when possible.
_diffrn.ambient_pressure_su
Standard Uncertainty of the Mean hydrostatic pressure at which intensities were measured.
_diffrn.ambient_temperature
Mean temperature at which intensities were measured.
_diffrn.ambient_temperature_details
A description of special aspects of temperature control during data collection.
_diffrn.ambient_temperature_gt
Mean temperature above which intensities were measured. These items allow for a temperature range to be given. _diffrn.ambient_temperature should be used in preference to this item when possible.
_diffrn.ambient_temperature_lt
Mean temperature below which intensities were measured. These items allow for a temperature range to be given. _diffrn.ambient_temperature should be used in preference to this item when possible.
_diffrn.ambient_temperature_su
Standard Uncertainty of the mean temperature at which intensities were measured.
_diffrn.crystal_support
The physical device used to support the crystal during data collection.
_diffrn.crystal_treatment
Remarks about how the crystal was treated prior to intensity measurement. Particularly relevant when intensities were measured at low temperature.
_diffrn.measured_fraction_theta_full
Fraction of unique (symmetryindependent) reflections measured out to _diffrn_reflns.theta_full.
_diffrn.measured_fraction_theta_max
Fraction of unique (symmetryindependent) reflections measured out to _diffrn_reflns.theta_max.
_diffrn.special_details
Special details of the diffraction measurement process. Should include information about source instability, crystal motion, degradation, etc.
_diffrn.symmetry_description
Recorded diffraction point symmetry, systematic absences and possible space group(s) or superspace group(s) compatible with these.
DIFFRN_ATTENUATOR
The CATEGORY of data items which specify the attenuators used in the diffraction source.
_diffrn_attenuator.code•
Code identifying a particular attenuator setting; referenced by the _diffrn_refln.attenuator_code which is stored with the intensities.
_diffrn_attenuator.material
Description of the material from which the attenuator is made.
_diffrn_attenuator.scale
The scale factor applied to a measured intensity if it is reduced by an attenuator identified by _diffrn_attenuator.code.
DIFFRN_DETECTOR
The CATEGORY of data items which specify the detectors used in the in the measurement of diffraction intensities.
_diffrn_detector.area_resol_mean
The resolution limit of an area diffraction radiation detector.
_diffrn_detector.description
Description of the type of diffraction radiation detector.
_diffrn_detector.details
Description of special aspects of the radiation detector.
_diffrn_detector.dtime
The maximum time between two detector signals that cannot be resolved.
_diffrn_detector.make
The make, model or name of the diffraction radiation detector.
DIFFRN_MEASUREMENT
The CATEGORY of data items which specify the details of the diffraction measurement.
_diffrn_measurement.details
Description of special aspects of the diffraction measurement.
_diffrn_measurement.device_class
Type of goniometer device used to mount and orient the specimen.
_diffrn_measurement.device_details
Details of the goniometer device used in the diffraction experiment.
_diffrn_measurement.device_make
The make, model or name of the goniometer device used.
_diffrn_measurement.method
Description of scan method used to measure diffraction intensities.
_diffrn_measurement.specimen_support
Mounting method for the crystal specimum during data collection.
DIFFRN_ORIENT
The CATEGORY of data items which specify the orientation of the crystal axes to the diffractometer goniometer.
DIFFRN_ORIENT_MATRIX
The CATEGORY of data items which specify the matrix specifying the orientation of the crystal axes to the diffractometer goniometer.
_diffrn_orient_matrix.type
Description of orientation matrix and how it should be applied to define the orientation of the crystal with respect to the diffractometer axes.
_diffrn_orient_matrix.UB_11
(Generic definition) The set of data items which specify the elements of the matrix of the orientation of the crystal axes to the diffractometer goniometer.
_diffrn_orient_matrix.UB_12
(Generic definition) The set of data items which specify the elements of the matrix of the orientation of the crystal axes to the diffractometer goniometer.
_diffrn_orient_matrix.UB_13
(Generic definition) The set of data items which specify the elements of the matrix of the orientation of the crystal axes to the diffractometer goniometer.
_diffrn_orient_matrix.UB_21
(Generic definition) The set of data items which specify the elements of the matrix of the orientation of the crystal axes to the diffractometer goniometer.
_diffrn_orient_matrix.UB_22
(Generic definition) The set of data items which specify the elements of the matrix of the orientation of the crystal axes to the diffractometer goniometer.
_diffrn_orient_matrix.UB_23
(Generic definition) The set of data items which specify the elements of the matrix of the orientation of the crystal axes to the diffractometer goniometer.
_diffrn_orient_matrix.UB_31
(Generic definition) The set of data items which specify the elements of the matrix of the orientation of the crystal axes to the diffractometer goniometer.
_diffrn_orient_matrix.UB_32
(Generic definition) The set of data items which specify the elements of the matrix of the orientation of the crystal axes to the diffractometer goniometer.
_diffrn_orient_matrix.UB_33
(Generic definition) The set of data items which specify the elements of the matrix of the orientation of the crystal axes to the diffractometer goniometer.
_diffrn_orient_matrix.UBIJ
The 3x3 matrix specifying the orientation of the crystal with respect to the diffractometer axes.
DIFFRN_ORIENT_REFLN
The CATEGORY of data items which specify the reflections used to calculate the matrix which gives the orientation of the crystal axes to the diffractometer goniometer.
_diffrn_orient_refln.angle_chi
(Generic definition) Diffractometer angle of a reflection measured at the centre of the diffraction peak and used to determine _diffrn_orient_matrix.UBIJ.
_diffrn_orient_refln.angle_kappa
(Generic definition) Diffractometer angle of a reflection measured at the centre of the diffraction peak and used to determine _diffrn_orient_matrix.UBIJ.
_diffrn_orient_refln.angle_omega
(Generic definition) Diffractometer angle of a reflection measured at the centre of the diffraction peak and used to determine _diffrn_orient_matrix.UBIJ.
_diffrn_orient_refln.angle_phi
(Generic definition) Diffractometer angle of a reflection measured at the centre of the diffraction peak and used to determine _diffrn_orient_matrix.UBIJ.
_diffrn_orient_refln.angle_psi
(Generic definition) Diffractometer angle of a reflection measured at the centre of the diffraction peak and used to determine _diffrn_orient_matrix.UBIJ.
_diffrn_orient_refln.angle_theta
(Generic definition) Diffractometer angle of a reflection measured at the centre of the diffraction peak and used to determine _diffrn_orient_matrix.UBIJ.
_diffrn_orient_refln.hkl•
Miller indices of a reflection used to define the orientation matrix.
_diffrn_orient_refln.index_h•
(Generic definition) The index of a reciprocal space vector.
_diffrn_orient_refln.index_k•
(Generic definition) The index of a reciprocal space vector.
_diffrn_orient_refln.index_l•
(Generic definition) The index of a reciprocal space vector.
DIFFRN_RADIATION
The CATEGORY of data items which specify the wavelength of the radiation used in measuring diffraction intensities. Items may be looped to identify and assign weights to distinct wavelength components from a polychromatic beam.
_diffrn_radiation.collimation
Description of the collimation or focusing applied to the radiation.
_diffrn_radiation.filter_edge
Absorption edge of the radiation filter used.
_diffrn_radiation.inhomogeneity
Halfwidth of the incident beam perpendicular to the diffraction plane.
_diffrn_radiation.monochromator
Description of the method used to obtain monochromatic radiation. If a monochromator crystal is used the material and the indices of the Bragg reflection are specified.
_diffrn_radiation.polarisn_norm
The angle, as viewed from the specimen, between the perpendicular component of the polarisation and the diffraction plane.
_diffrn_radiation.polarisn_ratio
Polarisation ratio of the diffraction beam incident on the crystal. It is the ratio of the perpendicularly polarised to the parallel polarised component of the radiation. The perpendicular component forms an angle of _diffrn_radiation.polarisn_norm to the normal to the diffraction plane of the sample (i.e. the plane containing the incident and reflected beams).
_diffrn_radiation.probe
Enumerated code for the nature of radiation used (i.e. name of subatomic particle or region of the electromagnetic spectrum).
_diffrn_radiation.type
Details of the radiation source or energy spectrum.
_diffrn_radiation.xray_symbol
IUPAC symbol for the Xray wavelength for probe radiation.
DIFFRN_RADIATION_WAVELENGTH
The CATEGORY of data items which specify the wavelength of the radiation used in measuring diffraction intensities. Items may be looped to identify and assign weights to distinct wavelength components from a polychromatic beam.
_diffrn_radiation_wavelength.details
Information about the determination of the radiation diffrn_radiation_wavelength that is not conveyed completely by an enumerated value of _diffrn_radiation_wavelength.determination.
_diffrn_radiation_wavelength.determination
Information about the determination of the radiation wavelength that is not conveyed completely by an enumerated value of _diffrn_radiation_wavelength.determination.
_diffrn_radiation_wavelength.id•
Code identifying a radiation used in the diffraction measurements. This is linked to _diffrn_refln.wavelength_id and _refln.wavelength_id
_diffrn_radiation_wavelength.value
Wavelength of radiation used in diffraction measurements.
_diffrn_radiation_wavelength.wt
Relative intensity of a radiation used in the diffraction measurements.
DIFFRN_REFLN
The CATEGORY of data items which specify the reflection measurements, prior to data reduction and merging.
_diffrn_refln.angle_chi
(Generic definition) Diffractometer angle at which the intensity is measured. This was calculated from the specified orientation matrix and the original measured cell dimensions before any subsequent transformations.
_diffrn_refln.angle_kappa
(Generic definition) Diffractometer angle at which the intensity is measured. This was calculated from the specified orientation matrix and the original measured cell dimensions before any subsequent transformations.
_diffrn_refln.angle_omega
(Generic definition) Diffractometer angle at which the intensity is measured. This was calculated from the specified orientation matrix and the original measured cell dimensions before any subsequent transformations.
_diffrn_refln.angle_phi
(Generic definition) Diffractometer angle at which the intensity is measured. This was calculated from the specified orientation matrix and the original measured cell dimensions before any subsequent transformations.
_diffrn_refln.angle_psi
(Generic definition) Diffractometer angle at which the intensity is measured. This was calculated from the specified orientation matrix and the original measured cell dimensions before any subsequent transformations.
_diffrn_refln.angle_theta
(Generic definition) Diffractometer angle at which the intensity is measured. This was calculated from the specified orientation matrix and the original measured cell dimensions before any subsequent transformations.
_diffrn_refln.attenuator_code
Code identifying any attenuator setting for this reflection.
_diffrn_refln.class_code
Code for reflection class, if assigned. e.g. modulated structures
_diffrn_refln.counts_bg_1
(Generic definition) The set of data items which specify the diffractometer counts. Background counts before the peak, background after the peak, net counts after background removed, counts for peak scan or position, and the total counts (background plus peak).
_diffrn_refln.counts_bg_2
(Generic definition) The set of data items which specify the diffractometer counts. Background counts before the peak, background after the peak, net counts after background removed, counts for peak scan or position, and the total counts (background plus peak).
_diffrn_refln.counts_net
(Generic definition) The set of data items which specify the diffractometer counts. Background counts before the peak, background after the peak, net counts after background removed, counts for peak scan or position, and the total counts (background plus peak).
_diffrn_refln.counts_peak
(Generic definition) The set of data items which specify the diffractometer counts. Background counts before the peak, background after the peak, net counts after background removed, counts for peak scan or position, and the total counts (background plus peak).
_diffrn_refln.counts_total
(Generic definition) The set of data items which specify the diffractometer counts. Background counts before the peak, background after the peak, net counts after background removed, counts for peak scan or position, and the total counts (background plus peak).
_diffrn_refln.detect_slit_horiz
Total slit aperture angle in the diffraction plane.
_diffrn_refln.detect_slit_vert
Total slit aperture angle perpendicular to the diffraction plane.
_diffrn_refln.elapsed_time
Elapsed time from the start to the end of the intensity measurement.
_diffrn_refln.hkl•
Miller indices of a measured reflection. These need not match the _refln.hkl values if a transformation of the original measured cell has taken place.
_diffrn_refln.index_h•
(Generic definition) The index of a reciprocal space vector.
_diffrn_refln.index_k•
(Generic definition) The index of a reciprocal space vector.
_diffrn_refln.index_l•
(Generic definition) The index of a reciprocal space vector.
_diffrn_refln.intensity_net
Net intensity calculated from the diffraction counts after the attenuator and standard scales have been applied.
_diffrn_refln.intensity_net_su
Standard uncertainty of the net intensity calculated from the diffraction counts after the attenuator and standard scales have been applied.
_diffrn_refln.scale_group_code
Code identifying the scale applying to this reflection.
_diffrn_refln.scan_mode
Code identifying the mode of scanning with a diffractometer. See also _diffrn_refln.scan_width and _diffrn_refln.scan_mode_backgd.
_diffrn_refln.scan_mode_backgd
Code identifying mode of scanning to measure the background intensity.
_diffrn_refln.scan_rate
Angular rate of scanning a reflection to measure the intensity.
_diffrn_refln.scan_time_backgd
Time spent measuring background counts.
_diffrn_refln.scan_width
Angular scan width when measuring the peak intensity.
_diffrn_refln.sin_theta_over_lambda
(sin theta)/lambda value for this reflection.
_diffrn_refln.standard_code
Code identifying reflections measured repeated as standard intensity. Must match a _diffrn_standard_refln.code values OR set to . if it was not used as a intensity standard.
_diffrn_refln.wavelength
Mean wavelength of radiation used to measure this intensity.
_diffrn_refln.wavelength_id
Code identifying the wavelength in the diffrn_radiation_wavelength list.
DIFFRN_REFLNS
The CATEGORY of data items which specify the overall reflection measurement information.
_diffrn_reflns.av_R_equivalents
The residual [sum avdel(I) / sum av(I)] for symmetryequivalent reflections used to calculate the average intensity av(I). The avdel(I) term is the average absolute difference between av(I) and the individual symmetryequivalent intensities.
_diffrn_reflns.av_sunetI_over_netI
Recorded [sum su(netI) / sum netI] for all measured reflections.
_diffrn_reflns.Laue_measured_fraction_full
Fraction of Laue_group unique reflections (symmetryindependent in the Laue group) measured out to the resolution given in _diffrn_reflns.resolution_full or _diffrn_reflns.theta_full. The Laue group always contains a centre of symmetry so that the reflection h,k,l is always equivalent to the reflection h,k,l even in space groups without a centre of symmetry. This number should not be less than 0.95, since it represents the fraction of reflections measured in the part of the diffraction pattern that is essentially complete.
_diffrn_reflns.Laue_measured_fraction_max
Fraction of Lauegroup unique reflections (symmetryindependent in the Laue group) measured out to the resolution given in _diffrn_reflns.resolution_max or _diffrn_reflns.theta_max. The Laue group always contains a centre of symmetry so that the reflection h,k,l is always equivalent to the reflection h,k,l even in space groups without a centre of symmetry.
_diffrn_reflns.limit_h_max
(Generic definition) The index of a reciprocal space vector.
_diffrn_reflns.limit_h_min
(Generic definition) The index of a reciprocal space vector.
_diffrn_reflns.limit_k_max
(Generic definition) The index of a reciprocal space vector.
_diffrn_reflns.limit_k_min
(Generic definition) The index of a reciprocal space vector.
_diffrn_reflns.limit_l_max
(Generic definition) The index of a reciprocal space vector.
_diffrn_reflns.limit_l_min
(Generic definition) The index of a reciprocal space vector.
_diffrn_reflns.limit_max
Maximum Miller indices of measured diffraction reflections.
_diffrn_reflns.limit_min
Minimum Miller indices of meas.ued diffraction reflections.
_diffrn_reflns.number
Total number of measured intensities, excluding reflections that are classed as systematically absent arising from translational symmetry in the crystal unit cell.
_diffrn_reflns.point_measured_fraction_full
Fraction of crystal pointgroup unique reflections (i.e. symmetryindependent in the crystal point group) measured out to the resolution given in _diffrn_reflns.resolution_full or _diffrn_reflns.theta_full. For space groups that do not contain a centre of symmetry the reflections h,k,l and h,k,l are independent. This number should not be less than 0.95, since it represents the fraction of reflections measured in the part of the diffraction pattern that is essentially complete.
_diffrn_reflns.point_measured_fraction_max
Fraction of crystal pointgroup unique reflections (i.e. symmetryindependent in the crystal point group) measured out to the resolution given in _diffrn_reflns.resolution_max or _diffrn_reflns.theta_max. For space groups that do not contain a centre of symmetry the reflections h,k,l and h,k,l are independent.
_diffrn_reflns.reduction_process
How intensities were reduced to structurefactor magnitudes.
_diffrn_reflns.resolution_full
The resolution at which the measured reflection count is close to complete. The fraction of unique reflections measured out to this angle is given by _diffrn.measured_fraction_theta_full.
_diffrn_reflns.resolution_max
Maximum resolution of the measured diffraction pattern. The fraction of unique reflections measured out to this angle is given by _diffrn.measured_fraction_theta_max.
_diffrn_reflns.theta_full
Theta angle at which the count of measured reflections is almost complete. The fraction of unique reflections measured out to this angle is given by _diffrn.measured_fraction_theta_full.
_diffrn_reflns.theta_max
Maximum theta angle of the measured reflections.
_diffrn_reflns.theta_min
Minimum theta angle of the measured reflections.
DIFFRN_REFLNS_CLASS
The CATEGORY of data items which specify different classes of reflections in the raw measured diffraction data.
_diffrn_reflns_class.av_R_eq
Residual [sum avdel(I)/sumav(I)] for symmetryequivalent reflections used to calculate the average intensity av(I). The avdel(I) term is the average absolute difference between av(I) and the individual intensities.
_diffrn_reflns_class.av_suI_over_I
Recorded [sumsu(net I)/sumnet I] in a reflection class.
_diffrn_reflns_class.code•
Code identifying a reflection class.
_diffrn_reflns_class.d_res_high
Highest resolution in reflection class i.e. smallest d value in class.
_diffrn_reflns_class.d_res_low
Lowest resolution in reflection class i.e. largest d value in class.
_diffrn_reflns_class.description
Description of a reflection class.
_diffrn_reflns_class.number
Number of measured intensities for a reflection class, excluding the systematic absences arising from centring translations.
DIFFRN_REFLNS_TRANSF_MATRIX
The CATEGORY of data items which specify the elements of the matrix used to transform the reflection indices _diffrn_refln.hkl into _refln.hkl. 11 12 13 (h k l) diffraction 21 22 23 = (h' k' l') 31 32 33
_diffrn_reflns_transf_matrix.11
(Generic definition) The set of data items which specify the elements of the matrix used to transform the reflection indices _diffrn_refln.hkl into _refln.hkl.
_diffrn_reflns_transf_matrix.12
(Generic definition) The set of data items which specify the elements of the matrix used to transform the reflection indices _diffrn_refln.hkl into _refln.hkl.
_diffrn_reflns_transf_matrix.13
(Generic definition) The set of data items which specify the elements of the matrix used to transform the reflection indices _diffrn_refln.hkl into _refln.hkl.
_diffrn_reflns_transf_matrix.21
(Generic definition) The set of data items which specify the elements of the matrix used to transform the reflection indices _diffrn_refln.hkl into _refln.hkl.
_diffrn_reflns_transf_matrix.22
(Generic definition) The set of data items which specify the elements of the matrix used to transform the reflection indices _diffrn_refln.hkl into _refln.hkl.
_diffrn_reflns_transf_matrix.23
(Generic definition) The set of data items which specify the elements of the matrix used to transform the reflection indices _diffrn_refln.hkl into _refln.hkl.
_diffrn_reflns_transf_matrix.31
(Generic definition) The set of data items which specify the elements of the matrix used to transform the reflection indices _diffrn_refln.hkl into _refln.hkl.
_diffrn_reflns_transf_matrix.32
(Generic definition) The set of data items which specify the elements of the matrix used to transform the reflection indices _diffrn_refln.hkl into _refln.hkl.
_diffrn_reflns_transf_matrix.33
(Generic definition) The set of data items which specify the elements of the matrix used to transform the reflection indices _diffrn_refln.hkl into _refln.hkl.
_diffrn_reflns_transf_matrix.TIJ
Elements of the matrix used to transform the diffraction reflection indices _diffrn_refln.hkl into the _refln.hkl indices. 11 12 13 (h k l) diffraction 21 22 23 = (h' k' l') 31 32 33
DIFFRN_SCALE_GROUP
The CATEGORY of data items which specify the groups of reflections in the raw measured diffraction data with different relative scales.
_diffrn_scale_group.code•
Code identifying a specific scale group of reflections (e.g. for multifilm or multicrystal data). The code must match a _diffrn_refln.scale_group_code in the diffrn_refln list.
_diffrn_scale_group.I_net
Scale for a specific measurement group of eflections. Is multiplied with the net intensity to place all intensities on a common scale.
DIFFRN_SOURCE
The CATEGORY of data items which specify information about the radiation source.
_diffrn_source.current
Generator current at which the radiation source device was operated.
_diffrn_source.details
General description of the radiation source device.
_diffrn_source.device
Enumerated code for the device providing the source of radiation.
_diffrn_source.make
Description of the make, model or name of the source device.
_diffrn_source.power
Generator power at which the radiation source device was operated.
_diffrn_source.size
Description of the collimated source beam as viewed from the sample.
_diffrn_source.take_off_angle
The complement of the angle in degrees between the normal to the surface of the Xray tube target and the primary Xray beam for beams generated by traditional Xray tubes.
_diffrn_source.target
Chemical element symbol for the radiation source target (usually the anode). This can be used also for spallation sources.
_diffrn_source.voltage
Generator voltage at which the radiation source device was operated.
DIFFRN_STANDARD
The CATEGORY of data items which specify information about the standard reflections used in the diffraction measurement process.
_diffrn_standard.decay_percent
The percentage decrease in the mean of the intensities for the standard reflections at the start to the finish of the measurement process. This value affords a measure of the overall decay in crystal quality during measurement. Negative values only occur in exceptional instances where the final intensities are greater than the initial ones. If no measurable decay has occurred, the standard uncertainty should be quoted to indicate the maximum possible value the decay might have. A range of 3 standard uncertainties is considered possible. Thus 0.0(1) would indicate a decay of less than 0.3% or an enhancement of less than 0.3%.
_diffrn_standard.interval_count
Reflection count between the standard reflection measurements.
_diffrn_standard.interval_time
Time between the standard reflection measurements.
_diffrn_standard.number
Number of unique standard reflections used in measurements.
_diffrn_standard.scale_su_average
The average standard uncertainty of the individual standard scales applied to the intensity data.
DIFFRN_STANDARD_REFLN
The CATEGORY of data items which specify the "standard" reflections measured repeatedly to monitor variations in intensity due to source flux, environment conditions or crystal quality.
_diffrn_standard_refln.code
Code identifying a standard reflection used to monitor source intensity variations or crystal degradation or movement during data collection.
_diffrn_standard_refln.hkl•
Miller indices of a standard reflection.
_diffrn_standard_refln.index_h•
(Generic definition) The index of a reciprocal space vector.
_diffrn_standard_refln.index_k•
(Generic definition) The index of a reciprocal space vector.
_diffrn_standard_refln.index_l•
(Generic definition) The index of a reciprocal space vector.
REFLN
The CATEGORY of data items used to describe the reflection data used in the refinement of a crystallographic structure model.
_refln.A_calc
The calculated real structurefactor component A =Fcalccos(phase)
_refln.A_meas
The measured real structurefactor component A =Fmeascos(phase)
_refln.B_calc
The calculated imaginary structurefactor component B =Fcalcsin(phase)
_refln.B_meas
The measured imaginary structurefactor component B =Fmeassin(phase)
_refln.class_code
Code identifying the class to which this reflection has been assigned. This code must match a value of _reflns_class.code. Reflections may be grouped into classes for a variety of purposes. For example, for modulated structures each reflection class may be defined by the number m=summ_{i}, where the m_{i} are the integer coefficients that, in addition to h,k,l, index the corresponding diffraction vector in the basis defined for the reciprocal lattice.
_refln.d_spacing
The distance in angstroms between lattice planes in the crystal with the indices _refln.hkl for this reflection.
_refln.F_calc
The structure factor amplitude for the reflection calculated from the atom site data.
_refln.F_complex
The structure factor vector for the reflection calculated from the atom site data.
_refln.F_meas
The structure factor amplitude for the reflection derived from the measured intensities.
_refln.F_meas_su
The standard uncertainty of the measured structure factor amplitude.
_refln.F_squared_calc
The structure factor amplitude squared for the reflection calculated from the atom site data.
_refln.F_squared_meas
The structure factor amplitude for the reflection derived from the measured intensities.
_refln.F_squared_meas_su
The standard uncertainty of the measured structure factor squared.
_refln.fom
The figure of merit m for this reflection.
int P~alpha~ exp(i*alpha) dalpha
m = 
int P~alpha~ dalpha
P~a~ = the probability that the phase angle a is correct
int is taken over the range alpha = 0 to 2 pi.
_refln.form_factor_table
Atomic scattering factor table for the scattering angle of this diffraction vector and atom types in structure.
_refln.hkl
The Miller indices as a reciprocal space vector.
_refln.include_status
Code indicating how the reflection was included in the refinement and Rfactor calculations.
_refln.index_h•
(Generic definition) The index of a reciprocal space vector.
_refln.index_k•
(Generic definition) The index of a reciprocal space vector.
_refln.index_l•
(Generic definition) The index of a reciprocal space vector.
_refln.intensity_calc
The intensity of the reflection calculated from the atom site data.
_refln.intensity_meas
The intensity of the reflection derived from the diffraction measurements.
_refln.intensity_meas_su
standard uncertainty of the measured intensity.
_refln.Lp_factor
The Lorentzpolarization factor appropriate for the instrument used to measure the diffraction intensity. This is applied to convert the net intensity into the measured F squared.
_refln.mean_path_length_tbar
Mean path length through the crystal for this diffraction vector.
_refln.phase_calc
The phase of the calculated structurefactor.
_refln.phase_meas
The phase of the measured structurefactor. This may be derived from the atom site data if available or from the phase solution process prior to determination of the structure.
_refln.refinement_status
Status code of reflection in the structure refinement process.
_refln.scale_group_code
Code identifying the scale (if there is more than one scale) used convert the measured structure factor to a common absolute value.
_refln.sin_theta_over_lambda
The (sin theta)/lambda value for this reflection.
_refln.symmetry_epsilon
The symmetry reinforcement factor corresponding to the number of times the reflection indices are generated identically from the spacegroup symmetry operations.
_refln.symmetry_multiplicity
The number of reflections symmetryequivalent under the Laue symmetry to the present reflection. In the Laue symmetry, Friedel opposites (h k l and h k l) are equivalent. Tables of symmetryequivalent reflections are available in International Tables for Crystallography, Volume A (1987), section 10.2.
_refln.wavelength
The mean wavelength in angstroms of radiation used to measure this reflection. This is an important parameter for data collected using energydispersive detectors or the Laue method.
_refln.wavelength_id
Code identifying the wavelength in DIFFRN_RADIATION_WAVELENGTH list.
REFLNS
The CATEGORY of data items used to specify parameters for the complete set of reflections used in the structure refinement process. Note that these parameters are often similar measures to those defined in the DIFFRN categories, but differ in that the parameters refer to the reduced/transformed reflections which have been used to refine the atom site data in the ATOM_SITE category. The DIFFRN definitions refer to the diffraction measurements and the raw reflection data.
_reflns.apply_dispersion_to_Fcalc
Yes or No flag on whether the anomalous dispersion scattering components will be applied in the F_complex calculation. See _refln.F_complex
_reflns.d_resolution_high
Highest resolution for the final REFLN data set. This corresponds to the smallest interpanar d value.
_reflns.d_resolution_low
Lowest resolution for the final REFLN data set. This corresponds to the largest interpanar d value.
_reflns.Friedel_coverage
The proportion of Friedel related reflections present in the number of the independent reflections specified by the item _reflns.number_total.
This proportion is calculated as the ratio:
[N(Crystal class)  N(Laue symmetry)] / N(Laue symmetry)
where, working from the @diffrn_refln_ list,
N(Crystal class) is the number of reflections obtained on
averaging under the symmetry of the crystal class
N(Laue symmetry) is the number of reflections obtained on
averaging under the Laue symmetry.
(a) For centrosymmetric structures its value is
necessarily equal to 0.0 as the crystal class
is identical to the Laue symmetry.
(b) For wholesphere data for a crystal in the space
group P1, _reflns.Friedel_coverage is equal to 1.0,
as no reflection h k l is equivalent to h k l
in the crystal class and all Friedel pairs
{h k l; h k l} have been measured.
(c) For wholesphere data in space group Pmm2, the value
will be < 1.0 because although reflections h k l and
h k l are not equivalent when h k l indices are
nonzero, they are when l=0.
(d) For a crystal in the group Pmm2 measurements of the
two inequivalent octants h >= 0, k >=0, l lead to the
same value as in (c), whereas measurements of the
two equivalent octants h >= 0, k, l >= 0 will lead to
a zero value for @reflns_Friedel_coverage.
_reflns.Friedel_fraction_full
The ratio of Friedel pairs measured to _diffrn_reflns.theta_full to the number theoretically possible (ignoring reflections in centric projections and systematic absences throughout). In contrast to _reflns.Friedel_coverage this can take values in the full range 0 to 1 for any noncentrosymmetric space group, and so one can see at a glance how completely the Friedel pairs have been measured. For centrosymmetric space groups the value would be given as notapplicable .
_reflns.Friedel_fraction_max
The ratio of Friedel pairs measured to _diffrn_reflns.theta_max to the number theoretically possible (ignoring reflections in centric projections and systematic absences throughout). In contrast to _reflns.Friedel_coverage this can take values in the full range 0 to 1 for any noncentrosymmetric space group, and so one can see at a glance how completely the Friedel pairs have been measured. For centrosymmetric space groups the value would be given as notapplicable .
_reflns.limit_h_max
(Generic definition) The index of a reciprocal space vector.
_reflns.limit_h_min
(Generic definition) The index of a reciprocal space vector.
_reflns.limit_k_max
(Generic definition) The index of a reciprocal space vector.
_reflns.limit_k_min
(Generic definition) The index of a reciprocal space vector.
_reflns.limit_l_max
(Generic definition) The index of a reciprocal space vector.
_reflns.limit_l_min
(Generic definition) The index of a reciprocal space vector.
_reflns.limit_max
Maximum Miller indices of refined diffraction reflections.
_reflns.limit_min
Minimum Miller indices of refined diffraction reflections.
_reflns.number_gt
Count of reflections in the REFLN set (not the DIFFRN_REFLN set) which are significantly intense (see _reflns.threshold_expression). It may include Friedel equivalent reflections (i.e. those which are equivalent under the Laue symmetry but inequivalent under the crystal class), depending to the nature of the structure and the procedures used.
_reflns.number_total
Number of reflections in the REFLN set (not the DIFFRN_REFLN set). It may include Friedel equivalent reflections (i.e. those which are equivalent under the Laue symmetry but inequivalent under the crystal class), depending to the nature of the structure and the procedures used.
_reflns.special_details
Description of the properties of the REFLN reflection list that is not given in other data items. Should include details about the averaging of symmetryequivalent reflections including Friedel pairs.
_reflns.threshold_expression
Description of the criterion used to classify a reflection as having a "significant intensity". This criterion is usually expressed in terms of a u(I) or u(F) threshold. "u" is the standard uncertainty.
REFLNS_CLASS
The CATEGORY of data items which specify the properties of reflections in specific classes of reflections.
_reflns_class.code•
Code identifying a reflection class.
_reflns_class.d_res_high
Highest resolution for the reflections in this class. This corresponds to the smallest interpanar d value.
_reflns_class.d_res_low
Lowest resolution for the reflections in this class. This corresponds to the largest interpanar d value.
_reflns_class.description
Description of a reflection class.
_reflns_class.number_gt
Count of reflections in this REFLN class (not the DIFFRN_REFLN set) which are significantly intense (see _reflns.threshold_expression). It may include Friedel equivalent reflections (i.e. those which are equivalent under the Laue symmetry but inequivalent under the crystal class), depending to the nature of the structure and the procedures used.
_reflns_class.number_total
Count of reflections in this REFLN class (not the DIFFRN_REFLN set). It may include Friedel equivalent reflections (those which are equivalent under the Laue symmetry but inequivalent under the crystal class), depending to the nature of the structure and the procedures used.
_reflns_class.R_factor_all
Residual factor for reflections in this class used in refinement.
sum  F(meas)  F(calc) 
R(F all) = 
sum  F(meas) 
F(meas) = the measured structurefactor amplitudes
F(calc) = the calculated structurefactor amplitudes
and the sum is taken over the specified reflections
_reflns_class.R_factor_gt
Residual factor for the reflections in this class judged significantly intense (i.e. greater than required by the _reflns.threshold_expression) and included in the refinement.
sum  F(meas_gt)  F(calc) 
R(F gt) = 
sum  F(meas_gt) 
F(meas) = the measured structurefactor amplitudes
F(calc) = the calculated structurefactor amplitudes
and the sum is taken over the specified reflections
_reflns_class.R_Fsqd_factor
Residual factor R(F^{2}) for reflections in this class judged significantly intense (i.e. greater than required by the _reflns.threshold_expression) and included in the refinement.
sum  F(meas_gt)^2^  F(calc)^2^ 
R(Fsqd gt) = 
sum F(meas_gt)^2^
F(meas_gt)^2^ = square of the 'observed' structurefactor
F(calc )^2^ = square of the calculated structurefactor
and the sum is taken over the specified reflections
_reflns_class.R_I_factor
Residual factor R(I) for reflections in this class judged significantly intense (i.e. greater than required by the _reflns.threshold_expression) and included in the refinement.
sum  I(meas_gt)  I(calc) 
R(I gt) = 
sum  I(meas_gt) 
I(meas_gt) = the net 'observed' intensity
I(calc ) = the net calculated intensity
and the sum is taken over the specified reflections
_reflns_class.wR_factor_all
For each reflection class, the weighted residual factors for all reflections included in the refinement. The reflections also satisfy the resolution limits established by _reflns_class.d_res_high and _reflns_class.d_res_low.
( sum w [ Y(meas)  Y(calc) ]^2^ )^1/2^
wR = (  )
( sum w Y(meas)^2^ )
Y(meas) = the measured amplitudes specified by
_refine_ls.structure_factor_coef
Y(calc) = the calculated amplitudes specified by
_refine_ls.structure_factor_coef
w = the leastsquares weights
and the sum is taken over the reflections of this class.
REFLNS_SCALE
The CATEGORY of data items which specify the scales needed to place measured structure factor coefficients on the same absolute scale.
_reflns_scale.group_code•
Code identifying a reflection scale group. These names need not correspond to _diffrn_scale_group.code names.
_reflns_scale.meas_F
Structure factor scale for this scale group.
_reflns_scale.meas_F_squared
Structure factor squared scale for this scale group.
_reflns_scale.meas_intensity
Net intensity scale for this scale group.
REFLNS_SHELL
The CATEGORY of data items which specify the information about reflections divided into shells bounded by d resolution limits.
_reflns_shell.d_res_high•
Highest resolution for the reflections in this shell. This corresponds to the smallest interpanar d value.
_reflns_shell.d_res_limits•
Resolution for the reflections in this shell stored as the list of lowest and highest values. This is the category key.
_reflns_shell.d_res_low•
Lowest resolution for the reflections in this shell. This corresponds to the largest interpanar d value.
_reflns_shell.meanI_over_suI_all
Ratio of the mean intensity in a shell to the mean standard uncertainty of the intensities in the shell.
_reflns_shell.meanI_over_suI_gt
Ratio of the mean intensity of significantly intense reflections (see _reflns.threshold_expression) in this shell to the mean standard uncertainty of the intensities in the shell.
_reflns_shell.number_measured_all
Total count of reflections measured for this resolution shell.
_reflns_shell.number_measured_gt
Number of reflections measured for this resolution shell which are significantly intense (see _reflns.threshold_expression).
_reflns_shell.number_possible
Count of symmetryunique reflections possible in this reflection shell.
_reflns_shell.number_unique_all
Count of symmetryunique reflections present in this reflection shell.
_reflns_shell.number_unique_gt
Number of symmetryunique reflections present in this reflection shell which are significantly intense (see _reflns.threshold_expression).
_reflns_shell.percent_possible_all
Percentage of reflections present in this shell over that possible.
_reflns_shell.percent_possible_gt
Percentage of reflections present in this shell which are significantly intense (see _reflns.threshold_expression), over that possible.
_reflns_shell.Rmerge_F_all
Rmerge(F) for all reflections in a given shell.
sum~i~ ( sum~j~  F~j~  <F>  )
Rmerge(F) = 
sum~i~ ( sum~j~ <F> )
F~j~ = the amplitude of the jth observation of reflection i
<F> = the mean of the amplitudes of all observations of
reflection i
sum~i~ is taken over all reflections
sum~j~ is taken over all observations of each reflection.
_reflns_shell.Rmerge_F_gt
Rmerge(F) for reflections in a shell which are significantly intense (see _reflns.threshold_expression). The residual merge expression is shown in the _reflns_shell.Rmerge_F_all definition.
_reflns_shell.Rmerge_I_all
Rmerge(I) for all reflections in a given shell.
sum~i~ ( sum~j~  I~j~  <I>  )
Rmerge(I) = 
sum~i~ ( sum~j~ <I> )
I~j~ = the intensity of the jth observation of reflection i
<I> = the mean of the intensities of all observations of
reflection i
sum~i~ is taken over all reflections
sum~j~ is taken over all observations of each reflection.
_reflns_shell.Rmerge_I_gt
Rmerge(I) for reflections in a shell which are significantly intense (see _reflns.threshold_expression). The residual merge expression is shown in the _reflns_shell.Rmerge_I_all definition.
EXPTL
The CATEGORY of data items used to specify the experimental work prior to diffraction measurements. These include crystallization crystal measurements and absorptioncorrection techniques used..
_exptl.crystals_number
Total number of crystals used in the measurement of intensities.
_exptl.method
The method used in the experiment.
_exptl.method_details
A description of special aspects of the experimental method.
_exptl.special_details
Details of the experiment prior to intensity measurement. See also _exptl_crystal.preparation
_exptl.transmission_factor_max
The calculated maximum value of the transmission factor for the specimen. Its value does not include the effects of absorption in the specimen mount. The presence of this item does not imply that the structure factors have been corrected for absorption. For the applied correction see _exptl_absorpt.correction_T_max.
_exptl.transmission_factor_min
The calculated minimum value of the transmission factor for the specimen. Its value does not include the effects of absorption in the specimen mount. The presence of this item does not imply that the structure factors have been corrected for absorption. For the applied correction see _exptl_absorpt.correction_T_max.
CELL
The CATEGORY of data items used to describe the parameters of the crystal unit cell and their measurement.
_cell.angle_alpha
(Generic definition) The angle between the bounding cell axes.
_cell.angle_alpha_su
(Generic definition) Standard uncertainty of the angle between the bounding cell axes.
_cell.angle_beta
(Generic definition) The angle between the bounding cell axes.
_cell.angle_beta_su
(Generic definition) Standard uncertainty of the angle between the bounding cell axes.
_cell.angle_gamma
(Generic definition) The angle between the bounding cell axes.
_cell.angle_gamma_su
(Generic definition) Standard uncertainty of the angle between the bounding cell axes.
_cell.atomic_mass
Atomic mass of the contents of the unit cell. This calculated from the atom sites present in the ATOM_TYPE list, rather than the ATOM_SITE lists of atoms in the refined model.
_cell.convert_Uij_to_betaij
The reciprocal space matrix for converting the U(ij) matrix of atomic displacement parameters to a dimensionless beta(IJ) matrix. The adp factor in a structure factor expression:
t = exp 2pi**2 ( U11 h h a* a* + ...... 2 U23 k l b* c* )
t = exp  0.25 ( B11 h h a* a* + ...... 2 B23 k l b* c* )
= exp  ( beta11 h h + ............ 2 beta23 k l )
The conversion of the U or B matrices to the beta matrix
beta = C U C = C B C /8pi**2
where C is conversion matrix defined here.
_cell.convert_Uiso_to_Uij
The reciprocal space matrix for converting the isotropic Uiso atomic displacement parameter to the anisotropic matrix Uij.
 1 cos(gamma*) cos(beta*) 
U[i,j] = Uiso *  cos(gamma*) 1 cos(alpha*) 
 cos(beta*) cos(alpha*) 1 
_cell.formula_units_Z
The number of the formula units in the unit cell as specified by _chemical_formula.structural, _chemical_formula.moiety or _chemical_formula.sum.
_cell.length_a
(Generic definition) The length of each cell axis.
_cell.length_a_su
(Generic definition) Standard uncertainty of the length of each cell axis.
_cell.length_b
(Generic definition) The length of each cell axis.
_cell.length_b_su
(Generic definition) Standard uncertainty of the length of each cell axis.
_cell.length_c
(Generic definition) The length of each cell axis.
_cell.length_c_su
(Generic definition) Standard uncertainty of the length of each cell axis.
_cell.metric_tensor
The direct space (covariant) metric tensor used to transform vectors and coordinates from real (direct) to reciprocal space.
_cell.orthogonal_matrix
Orthogonal matrix of the crystal unit cell. Definition uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_cell.reciprocal_angle_alpha
Reciprocal of the angle between _cell.length_b and _cell.length_c. Ref: Buerger, M. J. (1942). Xray Crystallography, p. 360. New York: John Wiley & Sons Inc.
_cell.reciprocal_angle_alpha_su
Standard Uncertainty of the Reciprocal of the angle between _cell.length_b and _cell.length_c.
_cell.reciprocal_angle_beta
Reciprocal of the angle between _cell.length_a and _cell.length_c. Ref: Buerger, M. J. (1942). Xray Crystallography, p. 360. New York: John Wiley & Sons Inc.
_cell.reciprocal_angle_beta_su
Standard Uncertainty of the Reciprocal of the angle between _cell.length_a and _cell.length_c.
_cell.reciprocal_angle_gamma
Reciprocal of the angle between _cell.length_a and _cell.length_b. Ref: Buerger, M. J. (1942). Xray Crystallography, p. 360. New York: John Wiley & Sons Inc.
_cell.reciprocal_angle_gamma_su
Standard Uncertainty of the Reciprocal of the angle between _cell.length_a and _cell.length_b.
_cell.reciprocal_length_a
Reciprocal of the _cell.length_a.
_cell.reciprocal_length_a_su
Standard Uncertainty of the reciprocal of the _cell.length_a.
_cell.reciprocal_length_b
Reciprocal of the _cell.length_b.
_cell.reciprocal_length_b_su
Standard Uncertainty of the reciprocal of the _cell.length_b.
_cell.reciprocal_length_c
Reciprocal of the _cell.length_c.
_cell.reciprocal_length_c_su
Standard Uncertainty of the reciprocal of the _cell.length_c.
_cell.reciprocal_metric_tensor
The reciprocal (contravariant) metric tensor used to transform vectors and coordinates from reciprocal space to real (direct) space.
_cell.reciprocal_orthogonal_matrix
Orthogonal matrix of the reciprocal space. The matrix may be used to transform the nonorthogonal vector h = (h,k,l) into the orthogonal indices p = (p,q,r)
M h = p
_cell.reciprocal_vector_a
Reciprocal of the _cell.vector_a.
_cell.reciprocal_vector_b
Reciprocal of the _cell.vector_b.
_cell.reciprocal_vector_c
Reciprocal of the _cell.vector_c.
_cell.special_details
Description of special aspects of the cell choice, noting possible alternative settings.
_cell.vector_a
The cell vector along the x axis.
_cell.vector_b
The cell vector along the y axis.
_cell.vector_c
The cell vector along the z axis.
_cell.volume
Volume of the crystal unit cell.
_cell.volume_su
Standard uncertainty of the volume of the crystal unit cell.
CELL_MEASUREMENT
The CATEGORY of data items used to describe the angles between the axes in the crystal unit cell.
_cell_measurement.pressure
The pressure at which the unitcell parameters were measured (not the pressure used to synthesize the sample).
_cell_measurement.pressure_su
The standard uncertainty value that the temperature of the pressure at which the unitcell parameters were measured
_cell_measurement.radiation
Description of the radiation used to measure the unitcell data.
_cell_measurement.reflns_used
Total number of reflections used to determine the unit cell. The reflections may be specified as cell_measurement_refln items.
_cell_measurement.temperature
The temperature at which the unitcell parameters were measured (not the temperature of synthesis).
_cell_measurement.temperature_su
The standard uncertainty value that the temperature of the unitcell parameters were measured
_cell_measurement.theta_max
Maximum theta scattering angle of reflections used to measure the crystal unit cell.
_cell_measurement.theta_min
Minimum theta scattering angle of reflections used to measure the crystal unit cell.
_cell_measurement.wavelength
Wavelength of the radiation used to measure the unit cell. If this is not specified, the wavelength is assumed to be the same as that given in _diffrn_radiation_wavelength.value
CELL_MEASUREMENT_REFLN
The CATEGORY of data items used to describe the reflection data used in the measurement of the crystal unit cell.
_cell_measurement_refln.hkl•
Miller indices of a reflection used to measure the unit cell.
_cell_measurement_refln.index_h•
(Generic definition) The index of a reciprocal space vector.
_cell_measurement_refln.index_k•
(Generic definition) The index of a reciprocal space vector.
_cell_measurement_refln.index_l•
(Generic definition) The index of a reciprocal space vector.
_cell_measurement_refln.theta
Theta angle of reflection used to measure the crystal unit cell.
CHEMICAL
The CATEGORY of data items which describe the composition and chemical properties of the compound under study. The formula data items must be consistent with the density, unitcell and Z values.
_chemical.absolute_configuration
Necessary conditions for this assignment are given by Flack, H. D. & Bernardinelli, G. (1999). Acta Cryst. A55, 908915. (http://www.iucr.org/paper?sh0129) Flack, H. D. & Bernardinelli, G. (2000). J. Appl. Cryst. 33, 11431148. (http://www.iucr.org/paper?ks0021)
_chemical.compound_source
Description of the source of the compound under study, or of the parent molecule if a simple derivative is studied. This includes the place of discovery for minerals or the actual source of a natural product.
_chemical.enantioexcess_bulk
The enantioexcess of the bulk material from which the crystals were grown. A value of 0.0 indicates the racemate. A value of 1.0 indicates that the compound is enantiomerically pure. Enantioexcess is defined in the IUPAC Recommendations (Moss et al., 1996). The composition of the crystal and bulk must be the same. Ref: Moss G. P. et al. (1996). Basic Terminology of Stereochemistry. Pure Appl. Chem., 68, 21932222. http://www.chem.qmul.ac.uk/iupac/stereo/index.html
_chemical.enantioexcess_bulk_technique
Technique used to determine the enantioexcess of the bulk compound.
_chemical.enantioexcess_crystal
The enantioexcess of the crystal used for the diffraction study. A value of 0.0 indicates the racemate. A value of 1.0 indicates that the crystal is enantiomerically pure. Enantioexcess is defined in the IUPAC Recommendations (Moss et al., 1996). Ref: Moss G. P. et al. (1996). Basic Terminology of Stereochemistry. Pure Appl. Chem., 68, 21932222. http://www.chem.qmul.ac.uk/iupac/stereo/index.html
_chemical.enantioexcess_crystal_technique
Technique used to determine the enantioexcess of the crystal.
_chemical.identifier_inchi
The IUPAC International Chemical Identifier (InChI) is a textual identifier for chemical substances, designed to provide a standard and humanreadable way to encode molecular information and to facilitate the search for such information in databases and on the web. Ref: McNaught, A. (2006). Chem. Int. (IUPAC), 28 (6), 1214. http://www.iupac.org/inchi/
_chemical.identifier_inchi_key
The InChIKey is a compact hashed version of the full InChI (IUPAC International Chemical Identifier), designed to allow for easy web searches of chemical compounds. See http://www.iupac.org/inchi/
_chemical.identifier_inchi_version
Version number of the InChI standard to which the associated chemical identifier string applies.
_chemical.melting_point
The temperature at which a crystalline solid changes to a liquid.
_chemical.melting_point_gt
A temperature above which the melting point lies. _chemical.melting_point should be used in preference where possible.
_chemical.melting_point_lt
A temperature below which the melting point lies. _chemical.melting_point should be used in preference where possible.
_chemical.name_common
Trivial name by which the compound is commonly known.
_chemical.name_mineral
Mineral name accepted by the International Mineralogical Association. Use only for natural minerals.
_chemical.name_structure_type
Commonly used structuretype name. Usually only applied to minerals or inorganic compounds.
_chemical.name_systematic
IUPAC or Chemical Abstracts full name of compound.
_chemical.optical_rotation
The optical rotation in solution of the compound is specified in the following format:
'[α]^TEMP^~WAVE~ = SORT (c = CONC, SOLV)'
where: TEMP is the temperature of the measurement in degrees Celsius,
WAVE is an indication of the wavelength of the light
used for the measurement,
CONC is the concentration of the solution given as the
mass of the substance in g in 100 ml of solution,
SORT is the signed value (preceded by a + or a  sign)
of 100.α/(l.c), where α is the signed optical
rotation in degrees measured in a cell of length l in
dm and c is the value of CONC in g, and
SOLV is the chemical formula of the solvent.
_chemical.properties_biological
A description of the biological properties of the material.
_chemical.properties_physical
A description of the physical properties of the material.
_chemical.temperature_decomposition
The temperature at which a crystalline solid decomposes.
_chemical.temperature_decomposition_gt
The temperature above which a crystalline solid decomposes. _chemical.temperature_decomposition should be used in preference.
_chemical.temperature_decomposition_lt
The temperature below which a crystalline solid decomposes. _chemical.temperature_decomposition should be used in preference.
_chemical.temperature_decomposition_su
Standard Uncertainty of the temperature at which a crystalline solid decomposes.
_chemical.temperature_sublimation
The temperature at which a crystalline solid sublimates.
_chemical.temperature_sublimation_gt
The temperature above which a crystalline solid sublimates. _chemical.temperature_sublimation should be used in preference.
_chemical.temperature_sublimation_lt
The temperature below which a crystalline solid sublimates. _chemical.temperature_sublimation should be used in preference.
_chemical.temperature_sublimation_su
Standard Uncertainty of the temperature at which a crystalline solid sublimates.
CHEMICAL_CONN_ATOM
The CATEGORY of data items which describe the 2D chemical structure of the molecular species. They allow a 2D chemical diagram to be reconstructed for use in a publication or in a database search for structural and substructural relationships. In particular, the chemical_conn_atom data items provide information about the chemical properties of the atoms in the structure. In cases where crystallographic and molecular symmetry elements coincide they must also contain symmetrygenerated atoms, so as to describe a complete chemical entity.
_chemical_conn_atom.charge
The net integer charge assigned to this atom. This is the formal charge assignment normally found in chemical diagrams.
_chemical_conn_atom.display_x
Cartesian coordinate (x) of the atom site in a chemical diagram. The coordinate origin is at the lower left corner, the x axis is horizontal.
_chemical_conn_atom.display_y
Cartesian coordinate (y) of the atom site in a chemical diagram. The coordinate origin is at the lower left corner, the y axis is vertical.
_chemical_conn_atom.NCA
Total number of connected atoms excluding terminal hydrogen atoms.
_chemical_conn_atom.NH
Total number of hydrogen atoms attached to this atom, regardless of whether they are included in the refinement or the atom_site list. This number will be the same as _atom_site.attached_hydrogens only if none of the hydrogen atoms appear in the atom_site list.
_chemical_conn_atom.number•
The chemical sequence number to be associated with this atom.
_chemical_conn_atom.type_symbol
A code identifying the atom type.
CHEMICAL_CONN_BOND
The CATEGORY of data items which specify the connections between the atoms sites in the chemical_conn_atom list and the nature of the chemical bond between these atoms. These are details about the twodimensional (2D) chemical structure of the molecular species. They allow a 2D chemical diagram to be reconstructed for use in a publication or in a database search for structural and substructural relationships.
_chemical_conn_bond.atom_1•
Index id of first atom in a bond connecting two atom sites.
_chemical_conn_bond.atom_2•
Index id of second atom in a bond connecting two atom sites.
_chemical_conn_bond.distance
The value that should be taken as the target for the chemical bond associated with the specified atoms, expressed as a distance.
_chemical_conn_bond.distance_su
The value that should be taken as the target for the chemical bond associated with the specified atoms, expressed as a distance.
_chemical_conn_bond.type
Code for the chemical bond type.
CHEMICAL_FORMULA
The CATEGORY of data items which specify the composition and chemical properties of the compound. The formula data items must agree with those that specify the density, unitcell and Z values.
The following rules apply to the construction of the data items
_chemical_formula.analytical, *.structural and *.sum. For the
data item *.moiety the formula construction is broken up into
residues or moieties, i.e. groups of atoms that form a molecular
unit or molecular ion. The rules given below apply within each
moiety but different requirements apply to the way that moieties
are connected (see _chemical_formula.moiety).

Only recognized element symbols may be used.

Each element symbol is followed by a count number. A count of 1 may be omitted.

A space or parenthesis must separate each cluster of (element symbol + count).

Where a group of elements is enclosed in parentheses, the multiplier for the group must follow the closing parentheses. That is, all element and group multipliers are assumed to be printed as subscripted numbers. [An exception to this rule exists for *.moiety formulae where pre and postmultipliers are permitted for molecular units].

Unless the elements are ordered in a manner that corresponds to their chemical structure, as in _chemical_formula.structural, the order of the elements within any group or moiety depends on whether or not carbon is present. If carbon is present, the order should be: C, then H, then the other elements in alphabetical order of their symbol. If carbon is not present, the elements are listed purely in alphabetic order of their symbol. This is the Hill system used by Chemical Abstracts. This ordering is used in _chemical_formula.moiety and _chemical_formula.sum.
_chemical_formula.iupac '[Mo (C O)4 (C18 H33 P)2]' _chemical_formula.moiety 'C40 H66 Mo O4 P2' _chemical_formula.structural '((C O)4 (P (C6 H11)3)2)Mo' _chemical_formula.sum 'C40 H66 Mo O4 P2' _chemical_formula.weight 768.81
_chemical_formula.analytical
Formula determined by standard chemical analysis including trace elements. Parentheses are used only for standard uncertainties (su’s).
_chemical_formula.iupac
Formula expressed in conformance with IUPAC rules for inorganic and metalorganic compounds where these conflict with the rules for any other chemical_formula entries. Typically used for formatting a formula in accordance with journal rules. This should appear in the data block in addition to the most appropriate of the other chemical_formula data names. Ref: IUPAC (1990). Nomenclature of Inorganic Chemistry. Oxford: Blackwell Scientific Publications.
_chemical_formula.moiety
Formula with each discrete bonded residue or ion shown as a
separate moiety. See above CHEMICAL_FORMULA for rules
for writing chemical formulae. In addition to the general
formulae requirements, the following rules apply:
1. Moieties are separated by commas ,.
2. The order of elements within a moiety follows general rule
5 in CHEMICAL_FORMULA.
3. Parentheses are not used within moieties but may surround
a moiety. Parentheses may not be nested.
4. Charges should be placed at the end of the moiety. The
Singlege + or  may be preceded by a numerical multiplier
and should be separated from the last (element symbol
count) by a space. Pre or postmultipliers may be used for
individual moieties.
_chemical_formula.structural
This formula should correspond to the structure as reported, i.e. trace elements not included in atom type and atom site lists should not be included. See category description for the rules for writing chemical formulae for inorganics, organometallics, metal complexes etc., in which bonded groups are preserved as discrete entities within parentheses, with postmultipliers as required. The order of the elements should give as much information as possible about the chemical structure. Parentheses may be used and nested as required. This formula should correspond to the structure as actually reported, i.e. trace elements not included in atomtype and atomsite lists should not be included (see also _chemical_formula.analytical).
_chemical_formula.sum
Chemical formulae in which all discrete bonded residues and ions are summed over the constituent elements, following the ordering given in rule 5 of the CATEGORY description. Parentheses normally not used.
_chemical_formula.weight
Mass corresponding to the formulae _chemical_formula.structural, *_iupac, *_moiety or *_sum and, together with the Z value and cell parameters yield the density given as _exptl_crystal.density_diffrn.
_chemical_formula.weight_meas
Formula mass measured by a nondiffraction experiment.
EXPTL_ABSORPT
The CATEGORY of data items used to specify the experimental details of the absorption measurements and corrections to the diffraction data.
_exptl_absorpt.coefficient_mu
Absorption coefficient mu calculated from the atomic content of the cell, the density and the radiation wavelength.
_exptl_absorpt.correction_T_max
Maximum transmission factor for the crystal and radiation applied to the measured intensities, it includes the correction for absorption by the specimen mount and diffractometer as well as by the specimen itself. These values give the transmission (T) factor by which measured intensities have been REDUCED due to absorption. Sometimes referred to as absorption correction A or 1/A* (see "Crystal Structure Analysis for Chemists and Biologists" by J.P. Glusker et al., Wiley)
_exptl_absorpt.correction_T_min
Maximum transmission factor for the crystal and radiation applied to the measured intensities, it includes the correction for absorption by the specimen mount and diffractometer as well as by the specimen itself. These values give the transmission (T) factor by which measured intensities have been REDUCED due to absorption. Sometimes referred to as absorption correction A ori 1/A* (see "Crystal Structure Analysis for Chemists and Biologists" by J.P. Glusker et al., Wiley)
_exptl_absorpt.correction_type
Code identifying the absorption correction type and method. The empirical approach should NOT be used if more detailed information on the crystal shape is available.
_exptl_absorpt.process_details
Description of the absorption correction process applied to the measured intensities. A literature reference should be supplied for psiscan or multiscan techniques.
EXPTL_CRYSTAL
The CATEGORY of data items used to specify information about crystals used in the diffraction measurements.
_exptl_crystal.colour
Colour description of a crystal as a list of the allowed exptl_crystal_appearance states for general, intensity and hue.
_exptl_crystal.density_diffrn
Crystal density calculated from crystal unit cell and atomic content.
_exptl_crystal.density_meas
Crystal density measured using standard chemical and physical methods.
_exptl_crystal.density_meas_gt
The value above which the density measured using standard chemical and physical methods lies. This item is used only when _exptl_crystal.density_meas cannot be employed. It is intended for use in reporting information in databases and archives which would be misleading if reported otherwise.
_exptl_crystal.density_meas_lt
The value below which the density measured using standard chemical and physical methods lies. This item is used only when _exptl_crystal.density_meas cannot be employed. It is intended for use in reporting information in databases and archives which would be misleading if reported otherwise.
_exptl_crystal.density_meas_su
Standard Uncertainty of the Crystal density measured using standard chemical and physical methods.
_exptl_crystal.density_meas_temp
Temperature at which _exptl_crystal.density_meas was determined.
_exptl_crystal.density_meas_temp_gt
Temperature above which the measured density was determined. This item is used only when exptl_crystal.density_meas_temp cannot be employed. It is intended for use in reporting values from databases which would be misleading if reported otherwise.
_exptl_crystal.density_meas_temp_lt
Temperature below which the measured density was determined. This item is used only when exptl_crystal.density_meas_temp cannot be employed. It is intended for use in reporting values from databases which would be misleading if reported otherwise.
_exptl_crystal.density_meas_temp_su
Standard Uncertainty of the Temperature at which _exptl_crystal.density_meas was determined.
_exptl_crystal.density_method
Description of method used to measure _exptl_crystal.density_meas.
_exptl_crystal.description
Description of the quality and habit of the crystal. The crystal dimensions should appear in the exptl_crystal_size category.
_exptl_crystal.F_000
Number of electrons in the crystal unit cell contributing to F(000). It may contain dispersion contributions, and is calculated as
F(000) = [ (sum f~r~)^2^ + (sum f~i~)^2^ ]^1/2^
f~r~ = real part of the scattering factors at theta = 0
f~i~ = imaginary part of the scattering factors at theta = 0
the sum is taken over each atom in the unit cell
For Xrays, nondispersive F(000) is a positive number and counts
the effective number of electrons in the unit cell; for neutrons,
nondispersive F(000) (which may be negative) counts the total
nuclear scattering power in the unit cell. See
http://reference.iucr.org/dictionary/F(000)
_exptl_crystal.id
Code identifying a crystal.
_exptl_crystal.preparation
Details of crystal growth and preparation of the crystals (e.g. mounting) prior to the intensity measurements.
_exptl_crystal.pressure_history
Details concerning the pressure history of the crystals.
_exptl_crystal.recrystallization_method
Method used to recrystallize the sample. Sufficient details should be given for the procedure to be repeated. Temperatures, solvents, flux or carrier gases with concentrations or pressures and ambient atmosphere details should be given.
_exptl_crystal.size_length
The length of needle/cylindrical crystals.
_exptl_crystal.size_max
The maximum dimension of a crystal.
_exptl_crystal.size_mid
The median dimension of a crystal.
_exptl_crystal.size_min
The minimum dimension of a crystal.
_exptl_crystal.size_rad
The radius of a spherical or cylindrical crystal.
_exptl_crystal.thermal_history
Details concerning the thermal history of the crystals.
EXPTL_CRYSTAL_APPEARANCE
The CATEGORY of ENUMERATION items used to specify information about the crystal colour and appearance.
_exptl_crystal_appearance.general
Appearance of the crystal as prescribed state codes.
_exptl_crystal_appearance.hue
Colour hue of the crystals as prescribed state codes.
_exptl_crystal_appearance.intensity
Colour intensity of the crystal as prescribed state codes.
EXPTL_CRYSTAL_FACE
The CATEGORY of data items which specify the dimensions of the crystal used in the diffraction measurements.
_exptl_crystal_face.diffr_chi
(Generic definition) Diffractometer angle setting when the perpendicular to the specified crystal face is aligned along a specified direction (e.g. the bisector of the incident and reflected beams in an optical goniometer.
_exptl_crystal_face.diffr_kappa
(Generic definition) Diffractometer angle setting when the perpendicular to the specified crystal face is aligned along a specified direction (e.g. the bisector of the incident and reflected beams in an optical goniometer.
_exptl_crystal_face.diffr_phi
(Generic definition) Diffractometer angle setting when the perpendicular to the specified crystal face is aligned along a specified direction (e.g. the bisector of the incident and reflected beams in an optical goniometer.
_exptl_crystal_face.diffr_psi
(Generic definition) Diffractometer angle setting when the perpendicular to the specified crystal face is aligned along a specified direction (e.g. the bisector of the incident and reflected beams in an optical goniometer.
_exptl_crystal_face.hkl
Miller indices of the crystal face.
_exptl_crystal_face.index_h•
(Generic definition) The index of a reciprocal space vector.
_exptl_crystal_face.index_k•
(Generic definition) The index of a reciprocal space vector.
_exptl_crystal_face.index_l•
(Generic definition) The index of a reciprocal space vector.
_exptl_crystal_face.perp_dist
Perpendicular distance of face to the centre of rotation of the crystal.
SPACE_GROUP
The CATEGORY of data items used to specify space group information about the crystal used in the diffraction measurements.
Spacegroup types are identified by their number as listed in
International Tables for Crystallography Volume A, or by their
Schoenflies symbol. Specific settings of the space groups can
be identified by their Hall symbol, by specifying their
symmetry operations or generators, or by giving the
transformation that relates the specific setting to the
reference setting based on International Tables Volume A and
stored in this dictionary.
The commonly used HermannMauguin symbol determines the spacegroup type uniquely but several different HermannMauguin symbols may refer to the same spacegroup type. A HermannMauguin symbol contains information on the choice of the basis, but not on the choice of origin.
Ref: International Tables for Crystallography (2002). Volume A, Spacegroup symmetry, edited by Th. Hahn, 5th ed. Dordrecht: Kluwer Academic Publishers.
_space_group.Bravais_type
The symbol denoting the lattice type (Bravais type) to which the translational subgroup (vector lattice) of the space group belongs. It consists of a lowercase letter indicating the crystal system followed by an uppercase letter indicating the lattice centring. The settingindependent symbol mS replaces the settingdependent symbols mB and mC, and the settingindependent symbol oS replaces the settingdependent symbols oA, oB and oC.
Ref: International Tables for Crystallography (2002). Volume A, Spacegroup symmetry, edited by Th. Hahn, 5th ed., p. 15. Dordrecht: Kluwer Academic Publishers.
_space_group.centring_type
Symbol for the lattice centring. This symbol may be dependent on the coordinate system chosen.
_space_group.crystal_system
The name of the system of geometric crystal classes of space groups (crystal system) to which the space group belongs. Note that rhombohedral space groups belong to the trigonal system.
_space_group.IT_coordinate_system_code
A qualifier taken from the enumeration list identifying which setting in International Tables for Crystallography Volume A (2002) (IT) is used. See IT Table 4.3.2.1, Section 2.2.16, Table 2.2.16.1, Section 2.2.16.1 and Fig. 2.2.6.4. This item is not computerinterpretable and cannot be used to define the coordinate system. Use space_group.transform* instead.
Ref: International Tables for Crystallography (2002). Volume A, Spacegroup symmetry, edited by Th. Hahn, 5th ed. Dordrecht: Kluwer Academic Publishers.
_space_group.IT_number
The number as assigned in International Tables for Crystallography Vol A, specifying the proper affine class (i.e. the orientation preserving affine class) of space groups (crystallographic space group type) to which the space group belongs. This number defines the space group type but not the coordinate system expressed.
_space_group.Laue_class
The HermannMauguin symbol of the geometric crystal class of the point group of the space group where a centre of inversion is added if not already present.
_space_group.multiplicity
Number of unique symmetry elements in the space group.
_space_group.name_HM_alt
_space_group.name_H_M_alt allows for any HermannMauguin symbol to be given. The way in which this item is used is determined by the user and in general is not intended to be interpreted by computer. It may, for example, be used to give one of the extended HermannMauguin symbols given in Table 4.3.1 of International Tables for Crystallography Vol. A (1995) or a HermannMauguin symbol for a conventional or unconventional setting. Each component of the space group name is separated by a space or underscore. The use of space is strongly recommended. The underscore is only retained because it was used in earlier archived files. It should not be used in new CIFs. Subscripts should appear without special symbols. Bars should be given as negative signs before the numbers to which they apply. The commonly used HermannMauguin symbol determines the space group type uniquely but a given space group type may be described by more than one HermannMauguin symbol. The space group type is best described using _space_group_IT_number. The HermannMauguin symbol may contain information on the choice of basis though not on the choice of origin. To define the setting uniquely use _space_group.name_Hall or list the symmetry operations.
_space_group.name_HM_alt_description
A freetext description of the code appearing in _space_group.name_HM_alt.
_space_group.name_HM_full
The full international HermannMauguin spacegroup symbol as defined in Section 2.2.3 and given as the second item of the second line of each of the spacegroup tables of Part 7 of International Tables for Crystallography Volume A (2002).
Each component of the spacegroup name is separated by a space or an underscore character. The use of a space is strongly recommended. The underscore is only retained because it was used in old CIFs. It should not be used in new CIFs.
Subscripts should appear without special symbols. Bars should be given as negative signs before the numbers to which they apply. The commonly used HermannMauguin symbol determines the spacegroup type uniquely but a given spacegroup type may be described by more than one HermannMauguin symbol. The spacegroup type is best described using _space_group.IT_number or _space_group.name_Schoenflies. The full international HermannMauguin symbol contains information about the choice of basis for monoclinic and orthorhombic space groups but does not give information about the choice of origin. To define the setting uniquely use _space_group.name_Hall, list the symmetry operations or generators, or give the transformation relating the setting used to the reference setting defined in this dictionary under _space_group.reference_setting.
Ref: International Tables for Crystallography (2002). Volume A, Spacegroup symmetry, edited by Th. Hahn, 5th ed. Dordrecht: Kluwer Academic Publishers.
_space_group.name_HM_ref
The short international HermannMauguin spacegroup symbol as defined in Section 2.2.3 and given as the first item of each spacegroup table in Part 7 of International Tables for Crystallography Volume A (2002).
Each component of the spacegroup name is separated by a space or an underscore character. The use of a space is strongly recommended. The underscore is only retained because it was used in old CIFs. It should not be used in new CIFs.
Subscripts should appear without special symbols. Bars should be given as negative signs before the numbers to which they apply. The short international HermannMauguin symbol determines the spacegroup type uniquely. However, the spacegroup type is better described using _space_group.IT_number or _space_group.name_Schoenflies. The short international HermannMauguin symbol contains no information on the choice of basis or origin. To define the setting uniquely use _space_group.name_Hall, list the symmetry operations or generators, or give the transformation that relates the setting to the reference setting defined in this dictionary under _space_group.reference_setting.
_space_group.name_HM_alt may be used to give the HermannMauguin symbol corresponding to the setting used.
In the enumeration list, each possible value is identified by spacegroup number and Schoenflies symbol.
Ref: International Tables for Crystallography (2002). Volume A, Spacegroup symmetry, edited by Th. Hahn, 5th ed. Dordrecht: Kluwer Academic Publishers.
_space_group.name_Hall
Space group symbol defined by Hall. Each component of the space group name is separated by a space or an underscore. The use of space is strongly recommended because it specifies the coordinate system. The underscore in the name is only retained because it was used in earlier archived files. It should not be used in new CIFs. Ref: Hall, S. R. (1981). Acta Cryst. A37, 517525 [See also International Tables for Crystallography, Vol.B (1993) 1.4 Appendix B]
_space_group.name_Schoenflies
The Schoenflies symbol as listed in International Tables for Crystallography Volume A denoting the proper affine class (i.e. orientationpreserving affine class) of space groups (spacegroup type) to which the space group belongs. This symbol defines the spacegroup type independently of the coordinate system in which the space group is expressed.
The symbol is given with a period, ., separating the Schoenflies point group and the superscript.
Ref: International Tables for Crystallography (2002). Volume A, Spacegroup symmetry, edited by Th. Hahn, 5th ed. Dordrecht: Kluwer Academic Publishers.
_space_group.Patterson_name_HM
The HermannMauguin symbol of the type of that centrosymmetric symmorphic space group to which the Patterson function belongs; see Table 2.2.5.1 in International Tables for Crystallography Volume A (2002).
A space separates each symbol referring to different axes. Underscores may replace the spaces, but this use is discouraged. Subscripts should appear without special symbols. Bars should be given as negative signs before the number to which they apply.
Ref: International Tables for Crystallography (2002). Volume A, Spacegroup symmetry, edited by Th. Hahn, 5th ed., Table 2.2.5.1. Dordrecht: Kluwer Academic Publishers.
_space_group.point_group_HM
The HermannMauguin symbol denoting the geometric crystal class of space groups to which the space group belongs, and the geometric crystal class of point groups to which the point group of the space group belongs.
SPACE_GROUP_GENERATOR
The CATEGORY of data items used to list generators for the space group
_space_group_generator.key•
Arbitrary identifier for each entry in the _space_group_generator.xyz list.
_space_group_generator.xyz
A parsable string giving one of the symmetry generators of the space group in algebraic form. If W is a matrix representation of the rotational part of the generator defined by the positions and signs of x, y and z, and w is a column of translations defined by the fractions, an equivalent position X' is generated from a given position X by
X' = WX + w.
(Note: X is used to represent the bold italic x in International Tables for Crystallography Volume A, Section 5.)
When a list of symmetry generators is given, it is assumed that the complete list of symmetry operations of the space group (including the identity operation) can be generated through repeated multiplication of the generators, that is, (W3, w3) is an operation of the space group if (W2,w2) and (W1,w1) [where (W1,w1) is applied first] are either operations or generators and:
W3 = W2 x W1 w3 = W2 x w1 + w2.
Ref: International Tables for Crystallography (2002). Volume A, Spacegroup symmetry, edited by Th. Hahn, 5th ed. Dordrecht: Kluwer Academic Publishers.
SPACE_GROUP_SYMOP
The CATEGORY of data items used to describe symmetry equivalent sites in the crystal unit cell.
_space_group_symop.id•
Index identifying each entry in the _space_group_symop.operation_xyz list. It is normally the sequence number of the entry in that list, and should be identified with the code n in the geometry symmetry codes of the form n_klm. The identity operation (i.e. _space_group_symop.operation_xyz set to x,y,z) should be set to 1.
_space_group_symop.operation_description
An optional text description of a particular symmetry operation of the space group.
_space_group_symop.operation_xyz
A parsable string giving one of the symmetry operations of the space group in algebraic form. If W is a matrix representation of the rotational part of the symmetry operation defined by the positions and signs of x, y and z, and w is a column of translations defined by fractions, an equivalent position X' is generated from a given position X by the equation
X' = WX + w
(Note: X is used to represent bold_italics_x in International
Tables for Crystallography Vol. A, Part 5)
When a list of symmetry operations is given, it must contain
a complete set of coordinate representatives which generates
all the operations of the space group by the addition of
all primitive translations of the space group. Such
representatives are to be found as the coordinates of
the generalequivalent position in International Tables for
Crystallography Vol. A (2002), to which it is necessary to
add any centring translations shown above the
generalequivalent position.
That is to say, it is necessary to list explicitly all the
symmetry operations required to generate all the atoms in
the unit cell defined by the setting used.
_space_group_symop.R
A matrix containing the symmetry rotation operations of a space group
 r11 r12 r13 
R =  r21 r22 r23 
 r31 r32 r33 
_space_group_symop.RT
The TRANSPOSE of the symmetry rotation matrix representing the point group opertions of the space group
 r11 r21 r31 
RT =  r12 r22 r32 
 r13 r23 r33 
_space_group_symop.Seitz_matrix
A matrix containing the symmetry operations of a space group in 4x4 Seitz format.
 r11 r12 r13 t1 
 R T   r21 r22 r23 t2 
 0 1   r31 r32 r33 t3 
 0 0 0 1 
_space_group_symop.T
A vector containing the symmetry translation operations of a space group.
SPACE_GROUP_WYCKOFF
Contains information about Wyckoff positions of a space group. Only one site can be given for each special position but the remainder can be generated by applying the symmetry operations stored in _space_group_symop.operation_xyz.
_space_group_Wyckoff.coords_xyz
Coordinates of one site of a Wyckoff position expressed in terms of its fractional coordinates (x,y,z) in the unit cell. To generate the coordinates of all sites of this Wyckoff position, it is necessary to multiply these coordinates by the symmetry operations stored in _space_group_symop.operation_xyz.
_space_group_Wyckoff.id•
An arbitrary code that is unique to a particular Wyckoff position.
_space_group_Wyckoff.letter
The Wyckoff letter associated with this position, as given in International Tables for Crystallography Volume A. The enumeration value α corresponds to the Greek letter alpha used in International Tables.
Ref: International Tables for Crystallography (2002). Volume A, Spacegroup symmetry, edited by Th. Hahn, 5th ed. Dordrecht: Kluwer Academic Publishers.
_space_group_Wyckoff.multiplicity
The multiplicity of this Wyckoff position as given in International Tables Volume A. It is the number of equivalent sites per conventional unit cell.
Ref: International Tables for Crystallography (2002). Volume A, Spacegroup symmetry, edited by Th. Hahn, 5th ed. Dordrecht: Kluwer Academic Publishers.
_space_group_Wyckoff.site_symmetry
The subgroup of the space group that leaves the point fixed. It is isomorphic to a subgroup of the point group of the space group. The sitesymmetry symbol indicates the symmetry in the symmetry direction determined by the HermannMauguin symbol of the space group (see International Tables for Crystallography Volume A, Section 2.2.12).
Ref: International Tables for Crystallography (2002). Volume A, Spacegroup symmetry, edited by Th. Hahn, 5th ed. Dordrecht: Kluwer Academic Publishers.
FUNCTION
The crystallographic functions the invoked in the definition methods of CORE STRUCTURE data items defined and used with in the Crystallographic Information Framework (CIF).
_function.AtomType
The function r = AtomType( s )
returns an atom type symbol (element name) from the atom site label.
_function.Closest
The function u, d = Closest( v, u )
returns the real coordinate vector U which is the closest cell
translated occurence of the vector V to the vector W. D is the
cell translation vector required to move V to U.
_function.SeitzFromJones
The function s = SeitzFromJones( j )
returns a 4x4 Seitz matrix from the Jones faithful representation of
the equivalent position which is a character string e.g. 1/2+x,x,z.
_function.SymEquiv
The function xyz' = SymEquiv( symop, xyz )
returns a fractional coordinate vector xyz' which is input vector
xyz transformed by the input symop 'n_pqr' applied to the symmetry
equivalent matrix extracted from the category space_group_symop.
_function.SymKey
The function m = SymKey( s )
returns an integer index to the Seitz matrices from the character
string of the form 'n_pqr'.
_function.SymLat
The function v = SymLat( s )
returns a vector of the cell translations applied to the coordinates
from the character string of the form 'n_pqr'. i.e. p5, q5, r5.
_function.Symop
The function s = Symop( n, t )
returns a character string of the form 'n_pqr' where n is the
symmetry equivalent site number and [p,q,r] is the cell translation
vector PLUS [5,5,5].
MODEL
Items in the MODEL Category specify data for the crystal structure postulated and modelled from the atomic coordinates derived and refined from the diffraction information. The structural model is described principally in terms of the geometry of the connected atom sites and the crystal symmetry in which they reside.
GEOM
The CATEGORY of data items used to specify the geometry of the structural model as derived from the atomic sites. The geometry is expressed in terms of the interatomic angles (GEOM_ANGLE data), covalent bond distances (GEOM_BOND data), contact distances (GEOM_CONTACT data), hydrogen bonds (GEOM_HBOND data) and torsion geometry (GEOM_TORSION data). Geometry data are usually redundant, in that they can be calculated from other more fundamental quantities in the data block. However, they serve the dual purposes of providing a check on the correctness of both sets of data and of enabling the most important geometric data to be identified for publication by setting the appropriate publication flag.
_geom.bond_distance_incr
Increment added to the bond radii for the atomic species to specify the maximum permitted "bonded" distance between two atom sites.
_geom.bond_distance_min
Minimum permitted "bonded" distance between two atom sites.
_geom.contact_distance_incr
Increment added to the bond radii for the atomic species to specify the maximum permitted "contact" distance between two "nonbonded" atom sites.
_geom.contact_distance_min
Minimum permitted "contact" distance between two "nonbonded" atom sites.
_geom.special_details
Description of geometry information not covered by the existing data names in the geometry categories, such as leastsquares planes.
GEOM_ANGLE
The CATEGORY of data items used to specify the geometry angles in the structural model as derived from the atomic sites.
_geom_angle.atom_site_label_1•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell.
_geom_angle.atom_site_label_2•
The unique identifier for the vertex atom of the angle.
_geom_angle.atom_site_label_3•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell.
_geom_angle.distances
The pair of distances between sites 1  2 and 2  3.
_geom_angle.publ_flag
Code signals if the angle is referred to in a publication or should be placed in a table of significant angles.
_geom_angle.site_symmetry_1•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
_geom_angle.site_symmetry_2•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
_geom_angle.site_symmetry_3•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
_geom_angle.value
Angle defined by the atoms located at atom_site_x/site_symmetry_x for x = 1,2,3. The vertex atom is at site x = 2.
_geom_angle.value_su
Standard Uncertainty of the angle defined by the sites identified by _geom_angle.id
GEOM_BOND
The CATEGORY of data items used to specify the geometry bonds in the structural model as derived from the atomic sites.
_geom_bond.atom_site_label_1•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell.
_geom_bond.atom_site_label_2•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell.
_geom_bond.distance
Intramolecular bond distance between the sites identified by _geom_bond.id
_geom_bond.distance_su
Standard Uncertainty of the intramolecular bond distance between the sites identified by _geom_bond.id
_geom_bond.multiplicity
The number of times the given bond appears in the environment of the atoms labelled _geom_bond.atom_site_label_1. In cases where the full list of bonds is given, one of the series of equivalent bonds may be assigned the appropriate multiplicity while the others are assigned a value of 0.
_geom_bond.publ_flag
This code signals whether the angle is referred to in a publication or should be placed in a table of significant angles.
_geom_bond.site_symmetry_1•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
_geom_bond.site_symmetry_2•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
_geom_bond.valence
Bond valence calculated from the bond distance.
GEOM_CONTACT
The CATEGORY of data items used to specify the interatomic contact distances in the structural model.
_geom_contact.atom_site_label_1•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell.
_geom_contact.atom_site_label_2•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell.
_geom_contact.distance
Intermolecular distance between the atomic sites identifyed by _geom_contact.id
_geom_contact.distance_su
Standard Uncertainty of the intermolecular distance between the atomic sites identified by _geom_contact.id
_geom_contact.publ_flag
This code signals whether the contact distance is referred to in a publication or should be placed in a list of significant contact distances.
_geom_contact.site_symmetry_1•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
_geom_contact.site_symmetry_2•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
GEOM_HBOND
The CATEGORY of data items used to specify the hydrogen bond distances in the structural model as derived from atomic sites.
_geom_hbond.angle_DHA
Angle subtended by the sites listed. The hydrogen at site H is at the apex of the angle.
_geom_hbond.angle_DHA_su
Angle subtended by the sites identifyed in _geom_hbond.id. The hydrogen at site H is at the apex of the angle.
_geom_hbond.atom_site_label_A•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell.
_geom_hbond.atom_site_label_D•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell.
_geom_hbond.atom_site_label_H•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell.
_geom_hbond.distance_DA
The set of data items which specify the distance between the three atom sites identified by _geom_hbond.id.
_geom_hbond.distance_DA_su
Standard Uncertainty of the set of data items which specify the distance between the three atom sites identified by _geom_hbond.id.
_geom_hbond.distance_DH
The set of data items which specify the distance between the three atom sites identified by _geom_hbond.id.
_geom_hbond.distance_DH_su
Standard Uncertainty of the set of data items which specify the distance between the three atom sites identified by _geom_hbond.id.
_geom_hbond.distance_HA
The set of data items which specify the distance between the three atom sites identified by _geom_hbond.id.
_geom_hbond.distance_HA_su
Standard Uncertainty of the set of data items which specify the distance between the three atom sites identified by _geom_hbond.id.
_geom_hbond.publ_flag
This code signals whether the hydrogenbond information is referred to in a publication or should be placed in a table of significant hydrogenbond geometry.
_geom_hbond.site_symmetry_A•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
_geom_hbond.site_symmetry_D•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
_geom_hbond.site_symmetry_H•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
GEOM_TORSION
The CATEGORY of data items used to specify the torsion angles in the structural model as derived from the atomic sites.
_geom_torsion.angle
Angle defined by the sites identifyed in _geom_torsion.id. The torsionangle definition should be that of Klyne and Prelog. The vector direction *_label_2 to *_label_3 is the viewing direction, and the torsion angle is the angle of twist required to superimpose the projection of the vector between site 2 and site 1 onto the projection of the vector between site 3 and site 4. Clockwise torsions are positive, anticlockwise torsions are negative. Ref: Klyne, W. & Prelog, V. (1960). Experientia, 16, 521523.
_geom_torsion.angle_su
Standard Uncertainty of the torsion angle.
_geom_torsion.atom_site_label_1•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell.
_geom_torsion.atom_site_label_2•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell.
_geom_torsion.atom_site_label_3•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell.
_geom_torsion.atom_site_label_4•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell.
_geom_torsion.distances
Distances between sites 1  2, 2  3 and 3  4.
_geom_torsion.publ_flag
Code signals if the torsion angle is required for publication.
_geom_torsion.site_symmetry_1•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
_geom_torsion.site_symmetry_2•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
_geom_torsion.site_symmetry_3•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
_geom_torsion.site_symmetry_4•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
MODEL_SITE
The CATEGORY of data items used to describe atomic sites and connections in the proposed atomic model.
_model_site.adp_eigen_system
The set of three adp eigenvales and associated eigenvectors in the form of 4 element List. Each list has the form
(val, vecX, vecY, vecZ)
where the vector elements are direction cosines to the orthogonal
axes X,Y,Z. The lists are sorted in descending magnitude of val.
That is, the list with the largest val is first, and the smallest
val is last.
_model_site.adp_matrix_beta
Matrix of dimensionless anisotropic atomic displacement parameters.
_model_site.Cartn_xyz
Vector of Cartesian (orthogonal angstrom) atom site coordinates.
_model_site.display_colour
Display colour code assigned to this atom site. Note that the possible colours are enumerated in the colour_RBG list, and the default code is enumerated in the colour_hue list.
_model_site.fract_xyz
Vector of fractional atom site coordinates.
_model_site.index
Index number of an atomic site in the connected molecule.
_model_site.label•
Code identifies a site in the atom_site category of data.
_model_site.mole_index
Index number of a distinct molecules in the cell, not related by symmetry.
_model_site.radius_bond
Atomic radius of atom located at this site.
_model_site.radius_contact
Atomic contact radius of atom specie located at this site.
_model_site.symop•
(Generic definition) The set of data items which specify the symmetry operation codes which must be applied to the atom sites involved in the geometry angle.
The symmetry code of each atom site as the symmetryequivalent position number n and the cell translation number klm. These numbers are combined to form the code n klm or n_klm.
The character string n_klm is composed as follows:
n refers to the symmetry operation that is applied to the coordinates stored in _atom_site.fract_xyz. It must match a number given in _symmetry_equiv.pos_site_id.
k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z
_model_site.type_symbol
Code to identify the atom specie(s) occupying this site.
VALENCE
The CATEGORY of items used to specify bond valence parameters used to calculate bond valences from bond lengths.
VALENCE_PARAM
The CATEGORY of items for listing bond valences.
_valence_param.atom_1
Atom type symbol for atom 1 forming a bond whose valence parameters are given in this category.
_valence_param.atom_1_valence
The valence (formal charge) of the atom 1 whose bond valence parameters are given in this category.
_valence_param.atom_2
Atom type symbol for atom 2 forming a bond whose valence parameters are given in this category.
_valence_param.atom_2_valence
The valence (formal charge) of the atom 2 whose bond valence parameters are given in this category.
_valence_param.B
The bond valence parameter B used in the expression s = exp[(Ro  R)/B] where s is the valence of bond length R.
_valence_param.details
Details of valence parameters of stated bond.
_valence_param.id•
Unique index loop number of the valence parameter loop.
_valence_param.ref_id
Code linking parameters to the key valence_ref.id key in the reference list in category VALENCE_REF.
_valence_param.Ro
The bond valence parameter Ro used in the expression s = exp[(Ro  R)/B] where s is the valence of bond length R.
VALENCE_REF
The CATEGORY of items for listing valence references.
_valence_ref.id•
Unique loop code of the valence references.
_valence_ref.reference
Literature reference from which the valence parameters identified by _valence_param.id were taken
PUBLICATION
The DICTIONARY group encompassing the CORE PUBLICATION data items defined and used with in the Crystallographic Information Framework (CIF).
AUDIT
The CATEGORY of data items used to record details about the creation and subsequent updating of the data block.
_audit.block_code
A unique block_code identifier for each revision.
_audit.creation_date
The date ddmmyyyy of each revision to the data.
_audit.creation_method
A description of how the revision was applied to the data.
_audit.schema
This dataname identifies the type of information contained in the datablock. Software written for one schema will not, in general, correctly interpret datafiles written against a different schema.
Specifically, each value of _audit.schema corresponds to a list of categories that were (potentially implicitly) restricted to a single packet in the default Base schema, but which can contain multiple packets in the specified schema. All categories containing child keys of the listed categories may also contain multiple packets and do not need to be listed.
The category list for each schema may instead be determined from
examination of the dictionaries that this datablock conforms to (see
_audit_conform.dictionary).
_audit.update_record
A description of the revision applied to the data.
AUDIT_AUTHOR
The CATEGORY of data items used for author(s) details.
_audit_author.address
The address of an author of this data block. If there are multiple authors, _audit_author_address is looped with _audit_author.name.
_audit_author.name•
The name of an author of this data block. If there are multiple authors, _audit_author.name is looped with _audit_author.address. The family name(s), followed by a comma and including any dynastic components, precedes the first name(s) or initial(s).
AUDIT_CONFORM
The CATEGORY of data items used describe dictionary versions by which data names in the current data block are conformant.
_audit_conform.dict_location
File name or uniform resource locator (URL) where the conformant data dictionary resides.
_audit_conform.dict_name
Name identifying highestlevel data dictionary defining data names used in this file.
_audit_conform.dict_version
Code for the version of data dictionary defining data names used in this file.
AUDIT_CONTACT_AUTHOR
The CATEGORY of data items used for contact author(s) details.
_audit_contact_author.address
The mailing address of the author of the data block to whom correspondence should be addressed.
_audit_contact_author.email
The electronic mail address of the author of the data block to whom correspondence should be addressed, in a form recognizable to international networks. The format of email addresses is given in Section 3.4, Address Specification, of Internet Message Format, RFC 2822, P. Resnick (Editor), Network Standards Group, April 2001.
_audit_contact_author.fax
Facsimile telephone number of the author submitting the manuscript and data block. The recommended style is the international dialing prefix, followed by the area code in parentheses, followed by the local number with no spaces. The earlier convention of including the international dialing prefix in parentheses is no longer recommended.
_audit_contact_author.name•
The name of the author of the data block to whom correspondence should be addressed. The family name(s), followed by a comma and including any dynastic components, precedes the first name(s) or initial(s).
_audit_contact_author.phone
Telephone number of author submitting the manuscript and data block. The recommended style is the international dialing prefix, followed by the area code in parentheses, followed by the local number and any extension number prefixed by x, with no spaces. The earlier convention of including the international dialing prefix in parentheses is no longer recommended.
AUDIT_LINK
The CATEGORY of data items used to record details about the relationships between data blocks in the current CIF.
_audit_link.block_code•
The value of _audit.block_code associated with a data block in the current file related to the current data block. The special value . may be used to refer to the current data block for completeness.
_audit_link.block_description
Description of the relationship of the referenced data block to the current one.
CITATION
Category of items describing literature cited in the publication.
_citation.abstract
Abstract for the citation. This is used most when the citation is extracted from a bibliographic database that contains full text or abstract information.
_citation.abstract_id_CAS
Chemical Abstracts Service (CAS) abstract identifier.
_citation.book_id_ISBN
International Standard Book Number (ISBN) for book chap. cited.
_citation.book_publisher
Publisher of the citation; relevant for book chapters.
_citation.book_publisher_city
Location of publisher of the citation; relevant for book chapters.
_citation.book_title
Title of the book in which the citation appeared.
_citation.coordinate_linkage
Code specifies whether this citation is concerned with precisely the set of coordinates given in the data block. If, for instance, the publication described the same structure, but the coordinates had undergone further refinement prior to creation of the data block, the value of this data item would be no.
_citation.country
Country of publication; for journal articles and book chapters.
_citation.database_id_CSD
Identifier (refcode) of the database record in the Cambridge Structural Database containing details of the cited structure.
_citation.database_id_Medline
i Medline accession number categorizing a bibliographic entry.
_citation.id•
Unique identifier to the CITATION list. A value of primary should be used to indicate the citation that the author(s) consider to be the most pertinent to the contents of the data block. Note that this item need not be a number; it can be any unique identifier.
_citation.journal_abbrev
Abbreviated name of the journal cited as given in the Chemical Abstracts Service Source Index.
_citation.journal_full
Full name of the journal cited; relevant for journal articles.
_citation.journal_id_ASTM
American Society for the Testing of Materials (ASTM) code assigned to the journal cited (also referred to as the CODEN designator of the Chemical Abstracts Service); relevant for journal articles.
_citation.journal_id_CSD
The Cambridge Structural Database (CSD) code assigned to the journal cited; relevant for journal articles. This is also the system used at the Protein Data Bank (PDB).
_citation.journal_id_ISSN
The International Standard Serial Number (ISSN) code assigned to the journal cited; relevant for journal articles.
_citation.journal_issue
Issue number of the journal cited; relevant for articles.
_citation.journal_volume
Volume number of the journal cited; relevant for articles.
_citation.language
Language in which the citation appears.
_citation.page_first
First page of citation; relevant for articles and book chapters.
_citation.page_last
Last page of citation; relevant for articles and book chapters.
_citation.special_details
Special aspects of the relationship of the data block contents to the literature item cited.
_citation.title
Title of citation; relevant for articles and book chapters.
_citation.year
Year of citation; relevant for articles and book chapters.
CITATION_AUTHOR
Category of items describing citation author(s) details.
_citation_author.citation_id•
Code identifier in the CITATION data list. The value of must match an identifier specified in the CITATION list.
_citation_author.name
Name of citation author; relevant for articles and book chapters. The family name(s), followed by a comma and including any dynastic components, precedes the first name(s) or initial(s).
_citation_author.ordinal•
Ordinal code specifies the order of the author’s name in the list of authors of the citation.
CITATION_EDITOR
Category of items describing citation editor(s) details.
_citation_editor.citation_id•
Code identifier in the CITATION list. The value must match an identifier specified by _citation.id in the CITATION list.
_citation_editor.name
Name of citation editor; relevant for book chapters. The family name(s), followed by a comma and including any dynastic components, precedes the first name(s) or initial(s).
_citation_editor.ordinal•
This data item defines the order of the editor’s name in the list of editors of a citation.
COMPUTING
The CATEGORY of data items used to record details of the computer programs used in the crystal structure analysis.
_computing.cell_refinement
Brief description of software used for cell_refinement.
_computing.diffrn_collection
Description of software used to measure diffraction data.
_computing.diffrn_reduction
Description of software used to convert diffraction data to measured structure factors.
_computing.molecular_graphics
Brief description of software used for molecular_graphics.
_computing.publication_material
Brief description of software used for publication_material.
_computing.structure_refinement
Brief description of software used for structure_refinement.
_computing.structure_solution
Brief description of software used for structure_solution.
DATABASE
The CATEGORY of data items recording database deposition.
_database.CSD_history
The history of changes made by the Cambridge Crystallographic Data Centre and incorporated into the Cambridge Structural Database (CSD).
_database.journal_ASTM
ASTM CODEN designator for a journal as given in the Chemical Source List maintained by the Chemical Abstracts Service.
_database.journal_CSD
The journal code used in the Cambridge Structural Database.
DATABASE_CODE
The CATEGORY of data items recording database deposition. These data items are assigned by database managers and should only appear in a CIF if they originate from that source.
_database_code.CAS
Code assigned by the Chemical Abstracts Service.
_database_code.COD
Code assigned by Crystallography Open Database (COD).
_database_code.CSD
Code assigned by the Cambridge Structural Database.
_database_code.depnum_ccdc_archive
Deposition numbers assigned by the Cambridge Crystallographic Data Centre (CCDC) to files containing structural information archived by the CCDC.
_database_code.depnum_ccdc_fiz
Deposition numbers assigned by the Fachinformationszentrum Karlsruhe (FIZ) to files containing structural information archived by the Cambridge Crystallographic Data Centre (CCDC).
_database_code.depnum_ccdc_journal
Deposition numbers assigned by various journals to files containing structural information archived by the Cambridge Crystallographic Data Centre (CCDC).
_database_code.ICSD
Code assigned by the Inorganic Crystal Structure Database.
_database_code.MDF
Code assigned in the Metals Data File.
_database_code.NBS
Code assigned by the NBS (NIST) Crystal Data Database.
_database_code.PDB
Code assigned by the Protein Data Base.
_database_code.PDF
Code assigned in the Powder Diffraction File.
DISPLAY
The CATEGORY of data items used to enumerate the display parameters used in the discipline.
DISPLAY_COLOUR
The CATEGORY of data items used to enumerate the display colour codes used in the discipline.
_display_colour.blue
(Generic definition) Integer value between 0 and 255 giving the intensity of a specific colour component (red, green or blue) for the RBG display colour code.
_display_colour.green
(Generic definition) Integer value between 0 and 255 giving the intensity of a specific colour component (red, green or blue) for the RBG display colour code.
_display_colour.hue•
Colour hue as an enumerated code.
_display_colour.red
(Generic definition) Integer value between 0 and 255 giving the intensity of a specific colour component (red, green or blue) for the RBG display colour code.
_display_colour.RGB
The redgreenblue intensities, bases 256, for each colour code.
JOURNAL
Category of items recording details about the bookkeeping by the journal staff when processing a CIF submitted for publication. The creator of a CIF will not normally specify these data items. The data names are not defined in the dictionary because they are for journal use only.
_journal.coden_ASTM
ASTM code assigned to journal.
_journal.coden_Cambridge
Cambridge Cryst. Data Centre code assigned to journal.
_journal.data_validation_number
Journal data items are defined by the journal staff.
_journal.issue
Issue identifier within the journal.
_journal.language
Language of the publication.
_journal.name_full
Full name of the journal.
_journal.page_first
First page of the publication in the journal.
_journal.page_last
Last page of the publication in the journal.
_journal.paper_category
Category of the publication in the journal.
_journal.paper_doi
DOI of the publication in the journal.
_journal.suppl_publ_number
Number of supplementary publication.
_journal.suppl_publ_pages
Number of pages in the supplementary publication.
_journal.validation_number
Data validation number assigned to journal.
_journal.volume
Volume number of the publication.
_journal.year
Year of the publication.
JOURNAL_COEDITOR
Category of items recording coeditor details.
_journal_coeditor.address
The postal address of the coeditor.
_journal_coeditor.code
The coeditor identifier.
_journal_coeditor.email
The email address of the coeditor.
_journal_coeditor.fax
The fax number of the coeditor.
_journal_coeditor.name
The name of the coeditor.
_journal_coeditor.notes
Notes on coeditor interaction wrt this publication.
_journal_coeditor.phone
The phone number of the coeditor.
JOURNAL_DATE
Category of items recording dates of publication processing.
_journal_date.accepted
Date the publication was accepted.
_journal_date.from_coeditor
Date the publication recieved from coeditor.
_journal_date.printers_final
Date the publication last sent to the printers.
_journal_date.printers_first
Date the publication first sent to the printers.
_journal_date.proofs_in
Date the publication proofs recieved.
_journal_date.proofs_out
Date the publication proofs sent out.
_journal_date.recd_copyright
Date completed copyright recieved.
_journal_date.recd_electronic
Date publication recieved electronically.
_journal_date.recd_hard_copy
Date publication recieved as hard copy.
_journal_date.to_coeditor
Date the publication sent to the coeditor.
JOURNAL_INDEX
Category of items describing publication indices.
_journal_index.id•
Index number identifier of the JOURNAL_INDEX category.
_journal_index.subterm
Subterm index assigned for the publication.
_journal_index.term
Term index assigned for the publication.
_journal_index.type
Type of index assigned for the publication.
JOURNAL_TECHEDITOR
Category of items recording details of the technical editor processing this publication.
_journal_techeditor.address
Postal address of the technical editor for this publication.
_journal_techeditor.code
Code of the technical editor for this publication.
_journal_techeditor.email
Email address of the technical editor for this publication.
_journal_techeditor.fax
Fax number of the technical editor for this publication.
_journal_techeditor.name
Name of the technical editor for this publication.
_journal_techeditor.notes
Notes of the technical editor for this publication.
_journal_techeditor.phone
Phone number of the technical editor for this publication.
PUBL
Data items in the PUBL category are used when submitting a manuscript for publication. They refer either to the paper as a whole, or to specific named elements within a paper (such as the title and abstract, or the Comment and Experimental sections of Acta Crystallographica Section C). The data items in the PUBL_BODY category should be used for the textual content of other submissions. Typically, each journal will supply a list of the specific items it requires in its Notes for Authors.
_publ.contact_letter
A letter submitted to the journal editor by the contact author.
PUBL_AUTHOR
Category of data items recording the author information.
_publ_author.address
The address of a publication author. If there is more than one author, this will be looped with _publ_author_name.
_publ_author.email
The email address of a publication author. If there is more than one author, this will be looped with _publ_author_name. The format of email addresses is given in Section 3.4, Address Specification, of Internet Message Format, RFC 2822, P. Resnick (Editor), Network Standards Group, April 2001.
_publ_author.footnote
A footnote accompanying an author’s name in the list of authors of a paper. Typically indicates sabbatical address, additional affiliations or date of decease.
_publ_author.id_iucr
Identifier in the IUCr contact database of a publication author. This identifier may be available from the World Directory of Crystallographers (http://wdc.iucr.org).
_publ_author.name•
The name of a publication author. If there are multiple authors, this will be looped with _publ_author.address. The family name(s), followed by a comma and including any dynastic components, precedes the first names or initials.
_publ_author.phone
Telephone number of the author submitting the manuscript and data block.
The recommended style starts with the international dialing
prefix, followed by the area code in parentheses, followed by the
local number and any extension number prefixed by 'x',
with no spaces. The earlier convention of including
the international dialing prefix in parentheses is no longer
recommended.
PUBL_BODY
Data items in the PUBL_BODY category permit labelling of different text sections within the body of a submitted paper. Note that these should not be used in a paper which has a standard format with sections tagged by specific data names (such as in Acta Crystallographica Section C). Typically, each journal will supply a list of the specific items it requires in its Notes for Authors.
_publ_body.contents
A text section of a submitted paper.
_publ_body.element
The functional role of the associated text section.
_publ_body.format
Enumerated state indicating the appropriate typesetting conventions for accented characters and special symbols in the text section.
_publ_body.label•
Unigue identifier for each part of the body of the paper.
_publ_body.title
Title of the associated section of text.
PUBL_CONTACT_AUTHOR
Category of items describing contact author(s) details.
_publ_contact_author.address
The address of the author submitting the manuscript and data block. This is the person contacted by the journal editorial staff.
_publ_contact_author.email
Email address in a form recognizable to international networks. The format of email addresses is given in Section 3.4, Address Specification, of Internet Message Format, RFC 2822, P. Resnick (Editor), Network Standards Group, April 2001.
_publ_contact_author.fax
Facsimile telephone number of the author submitting the manuscript and data block. The recommended style is the international dialing prefix, followed by the area code in parentheses, followed by the local number with no spaces. The earlier convention of including the international dialing prefix in parentheses is no longer recommended.
_publ_contact_author.id_iucr
Identifier in the IUCr contact database of the author submitting the manuscript and datablock. This identifier may be available from the World Directory of Crystallographers (http://wdc.iucr.org).
_publ_contact_author.name•
The name of the author(s) submitting the manuscript and data block. This is the person contacted by the journal editorial staff.
_publ_contact_author.phone
Telephone number of author submitting the manuscript and data block. The recommended style is the international dialing prefix, followed by the area code in parentheses, followed by the local number and any extension number prefixed by x, with no spaces. The earlier convention of including the international dialing prefix in parentheses is no longer recommended.
PUBL_MANUSCRIPT
Category of items describing the publication manuscript.
_publ_manuscript.creation
A description of the wordprocessor package and computer used to create the manuscript stored as publ_manuscript.processed.
_publ_manuscript.processed
The full manuscript of a paper (excluding possibly the figures and the tables) output in ASCII characters from a word processor. Information about the generation of this data item must be specified in the data item _publ_manuscript.creation.
_publ_manuscript.text
The full manuscript of a paper (excluding figures and possibly the tables) output as standard ASCII text.
PUBL_MANUSCRIPT_INCL_EXTRA
Category of data items that allow the authors of a manuscript to submit for publication data names that should be added to the standard request list employed by journal printing software. Although these fields are primarily intended to identify CIF data items that the author wishes to include in a published paper, they can also be used to identify data names created so that nonCIF items can be included in the publication. Note that *.item names MUST be enclosed in single quotes.
_publ_manuscript_incl_extra.defn
Yes/No flags whether the corresponding data item marked for inclusion in a journal request list is a standard CIF definition or not.
_publ_manuscript_incl_extra.info
A short note indicating the reason why the author wishes the corresponding data item marked for inclusion in the journal request list to be published.
_publ_manuscript_incl_extra.item•
The data name (i.e. Tag) of a specific data item included in the manuscript which is not normally requested by the journal. The values of this item are the extra data names (which MUST be enclosed in single quotes) that will be added to the journal request list.
PUBL_REQUESTED
CATEGORY of data items that enable the author to make specific requests to the journal office for processing.
_publ_requested.category
The category of paper submitted. For submission to Acta Crystallographica Section C or Acta Crystallographica Section E, ONLY those codes indicated for use with those journals should be used.
_publ_requested.coeditor_name
The name of the Coeditor whom the authors would like to process the submitted manuscript.
_publ_requested.journal
Name of the journal to which the manuscript is being submitted.
PUBL_SECTION
Manuscript section data if submitted in parts. see also _publ_manuscript.text and _publ_manuscript.processed. The _publ_section.exptl_prep, _publ_section.exptl_refinement and _publ_section.exptl_solution items are preferred for separating the chemical preparation, refinement and structure solution aspects of the experimental description.
_publ_section.abstract
The abstract of the submitted paper.
_publ_section.acknowledgements
The acknowledgements section of the submitted paper.
_publ_section.comment
The comment section of the submitted paper.
_publ_section.discussion
The discussion section of the submitted paper.
_publ_section.experimental
The experimental section of the submitted paper.
_publ_section.exptl_prep
The experimental preparation section of the submitted paper.
_publ_section.exptl_refinement
The experimental refinement section of the submitted paper.
_publ_section.exptl_solution
The experimental solution section of the submitted paper.
_publ_section.figure_captions
The figure captions of the submitted paper.
_publ_section.introduction
The introduction section of the submitted paper.
_publ_section.keywords
The keywords of the submitted paper.
_publ_section.references
The references section of the submitted paper.
_publ_section.related_literature
The related literature section of the submitted paper.
_publ_section.synopsis
The synopsis of the submitted paper.
_publ_section.table_legends
The table legends of the submitted paper.
_publ_section.title
The full title of the submitted paper.
_publ_section.title_footnote
Footnote (if any) to the title of the submitted paper.
STRUCTURE
The DICTIONARY group encompassing the CORE STRUCTURE data items defined and used with in the Crystallographic Information Framework (CIF).
ATOM
The CATEGORY of data items used to describe atomic information used in crystallographic structure studies.
ATOM_SITE
The CATEGORY of data items used to describe atom site information used in crystallographic structure studies.
_atom_site.adp_type
Code for type of atomic displacement parameters used for the site.
_atom_site.attached_hydrogens
Number of hydrogen atoms attached to the atom at this site excluding any H atoms for which coordinates (measured or calculated) are given.
_atom_site.B_equiv_geom_mean
Equivalent isotropic atomic displacement parameter, B(equiv), in angstroms squared, calculated as the geometric mean of the anisotropic atomic displacement parameters.
B(equiv) = (B~i~ B~j~ B~k~)^1/3^
B~n~ = the principal components of the orthogonalised B^ij^
The IUCr Commission on Nomenclature recommends against the use
of B for reporting atomic displacement parameters. U, being
directly proportional to B, is preferred.
_atom_site.B_equiv_geom_mean_su
Standard Uncertainty value for the Equivalent isotropic atomic displacement parameter, B(equiv), in angstroms squared, calculated as the geometric mean of the anisotropic atomic displacement parameters.
_atom_site.B_iso_or_equiv
Isotropic atomic displacement parameter, or equivalent isotropic atomic displacement parameter, B(equiv), in angstroms squared, calculated from anisotropic temperature factor parameters.
B(equiv) = (1/3) sum~i~[sum~j~(B^ij^ a*~i~ a*~j~ a~i~ a~j~)]
a = the realspace cell lengths
a* = the reciprocalspace cell lengths
B^ij^ = 8 pi^2^ U^ij^
Ref: Fischer, R. X. & Tillmanns, E. (1988). Acta Cryst. C44, 775776.
The IUCr Commission on Nomenclature recommends against the use
of B for reporting atomic displacement parameters. U, being
directly proportional to B, is preferred.
_atom_site.B_iso_or_equiv_su
Standard Uncertainty value for the Isotropic atomic displacement parameter, or equivalent isotropic atomic displacement parameter, B(equiv), in angstroms squared, calculated from anisotropic temperature factor parameters.
_atom_site.calc_attached_atom
The _atom_site.label of the atom site to which the geometry calculated atom site is attached.
_atom_site.calc_flag
A standard code to signal if the site coordinates have been determined from the intensities or calculated from the geometry of surrounding sites, or have been assigned dummy coordinates.
_atom_site.Cartn_x
(Generic definition) The atom site coordinates in angstroms specified according to a set of orthogonal Cartesian axes related to the cell axes as specified by the _atom_sites_Cartn_transform.axes description.
_atom_site.Cartn_x_su
(Generic definition) Standard uncertainty values of the atom site coordinates in angstroms specified according to a set of orthogonal Cartesian axes related to the cell axes as specified by the _atom_sites_Cartn_transform.axes description.
_atom_site.Cartn_xyz
Vector of Cartesian (orthogonal angstrom) atom site coordinates.
_atom_site.Cartn_y
(Generic definition) The atom site coordinates in angstroms specified according to a set of orthogonal Cartesian axes related to the cell axes as specified by the _atom_sites_Cartn_transform.axes description.
_atom_site.Cartn_y_su
(Generic definition) Standard uncertainty values of the atom site coordinates in angstroms specified according to a set of orthogonal Cartesian axes related to the cell axes as specified by the _atom_sites_Cartn_transform.axes description.
_atom_site.Cartn_z
(Generic definition) The atom site coordinates in angstroms specified according to a set of orthogonal Cartesian axes related to the cell axes as specified by the _atom_sites_Cartn_transform.axes description.
_atom_site.Cartn_z_su
(Generic definition) Standard uncertainty values of the atom site coordinates in angstroms specified according to a set of orthogonal Cartesian axes related to the cell axes as specified by the _atom_sites_Cartn_transform.axes description.
_atom_site.chemical_conn_number
This number links an atom site to the chemical connectivity list. It must match a number specified by _chemical_conn_atom.number.
_atom_site.constraints
A description of the constraints applied to parameters at this site during refinement. See also _atom_site.refinement_flags and _refine_ls.number_constraints.
_atom_site.description
A description of special aspects of this site. See also _atom_site.refinement_flags.
_atom_site.disorder_assembly
A code which identifies a cluster of atoms that show long range positional disorder but are locally ordered. Within each such cluster of atoms, _atom_site.disorder_group is used to identify the sites that are simultaneously occupied. This field is only needed if there is more than one cluster of disordered atoms showing independent local order.
_atom_site.disorder_group
A code that identifies a group of positionally disordered atom sites that are locally simultaneously occupied. Atoms that are positionally disordered over two or more sites (e.g. the H atoms of a methyl group that exists in two orientations) can be assigned to two or more groups. Sites belonging to the same group are simultaneously occupied, but those belonging to different groups are not. A minus prefix (e.g. "1") is used to indicate sites disordered about a special position.
_atom_site.fract_x
(Generic definition) Atom site coordinates as fractions of the cell length values.
_atom_site.fract_x_su
(Generic definition) Standard uncertainty value of the atom site coordinates as fractions of the cell length values.
_atom_site.fract_xyz
Vector of atom site coordinates projected onto the crystal unit cell as fractions of the cell lengths.
_atom_site.fract_y
(Generic definition) Atom site coordinates as fractions of the cell length values.
_atom_site.fract_y_su
(Generic definition) Standard uncertainty value of the atom site coordinates as fractions of the cell length values.
_atom_site.fract_z
(Generic definition) Atom site coordinates as fractions of the cell length values.
_atom_site.fract_z_su
(Generic definition) Standard uncertainty value of the atom site coordinates as fractions of the cell length values.
_atom_site.label•
(Generic definition) This label is a unique identifier for a particular site in the asymmetric unit of the crystal unit cell. It is made up of components, _atom_site.label_component_0 to *_6, which may be specified as separate data items. Component 0 usually matches one of the specified _atom_type.symbol codes. This is not mandatory if an _atom_site.type_symbol item is included in the atom site list. The _atom_site.type_symbol always takes precedence over an _atom_site.label in the identification of the atom type. The label components 1 to 6 are optional, and normally only components 0 and 1 are used. Note that components 0 and 1 are concatenated, while all other components, if specified, are separated by an underline character. Underline separators are only used if higherorder components exist. If an intermediate component is not used it may be omitted provided the underline separators are inserted. For example the label C233__ggg is acceptable and represents the components C, 233, '', and ggg. Each label may have a different number of components.
_atom_site.label_component_0
(Generic definition) Component_0 is normally a code which matches identically with one of the _atom_type.symbol codes. If this is the case then the rules governing the _atom_type.symbol code apply. If, however, the data item _atom_site.type_symbol is also specified in the atom site list, component 0 need not match this symbol or adhere to any of the _atom_type.symbol rules. Component_1 is referred to as the "atom number". When component 0 is the atom type code, it is used to number the sites with the same atom type. This component code must start with at least one digit which is not followed by a + or  sign (to distinguish it from the component 0 rules). Components_2 to 6 contain the identifier, residue, sequence, asymmetry identifier and alternate codes, respectively. These codes may be composed of any characters except an underline.
_atom_site.label_component_1
(Generic definition) See label_component_0 description.
_atom_site.label_component_2
(Generic definition) See label_component_0 description.
_atom_site.label_component_3
(Generic definition) See label_component_0 description.
_atom_site.label_component_4
(Generic definition) See label_component_0 description.
_atom_site.label_component_5
(Generic definition) See label_component_0 description.
_atom_site.label_component_6
(Generic definition) See label_component_0 description.
_atom_site.occupancy
The fraction of the atom type present at this site. The sum of the occupancies of all the atom types at this site may not significantly exceed 1.0 unless it is a dummy site. The value must lie in the 99.97% Gaussian confidence interval 3u =< x =< 1 + 3u. The _enumeration.range of 0.0:1.0 is thus correctly interpreted as meaning (0.0  3u) =< x =< (1.0 + 3u).
_atom_site.occupancy_su
Standard Uncertainty value for the The fraction of the atom type present at this site.
_atom_site.refinement_flags
A concatenated series of singleletter codes which indicate the refinement restraints or constraints applied to this site.
_atom_site.refinement_flags_adp
A code which indicates the refinement restraints or constraints applied to the atomic displacement parameters of this site.
_atom_site.refinement_flags_occupancy
A code which indicates the refinement restraints or constraints applied to the occupancy of this site.
_atom_site.refinement_flags_posn
A code which indicates the refinement restraints or constraints applied to the positional coordinates of this site.
_atom_site.restraints
A description of restraints applied to specific parameters at this site during refinement. See also _atom_site.refinement_flags and _refine_ls.number_restraints.
_atom_site.site_symmetry_multiplicity
The number of different sites that are generated by the application of the spacegroup symmetry to the coordinates given for this site. It is equal to the multiplicity given for this Wyckoff site in International Tables for Cryst. Vol. A (2002). It is equal to the multiplicity of the general position divided by the order of the site symmetry given in _atom_site.site_symmetry_order.
_atom_site.site_symmetry_order
The number of times application of the crystallographic symmetry to the coordinates for this site generates the same coordinates. That is: multiplicity of the general position  _atom_site.site_symmetry_multiplicity
_atom_site.tensor_beta
The symmetric anisotropic atomic displacement tensor beta[I,J] appears in a structure factor expression as:
t = exp [ beta11 h h + ............ 2 beta23 k l ]
It is related to the adp matrices U(IJ) and B(IJ) as follows:
t = exp 2pi**2 ( U11 h h a* a* + ...... 2 U23 k l b* c* )
t = exp  0.25 ( B11 h h a* a* + ...... 2 B23 k l b* c* )
_atom_site.type_symbol
A code to identify the atom specie(s) occupying this site. This code must match a corresponding _atom_type.symbol. The specification of this code is optional if component_0 of the _atom_site.label is used for this purpose. See _atom_type.symbol.
_atom_site.U_equiv_geom_mean
Equivalent isotropic atomic displacement parameter, U(equiv), in angstroms squared, calculated as the geometric mean of the anisotropic atomic displacement parameters.
U(equiv) = (U~i~ U~j~ U~k~)^1/3^
U~n~ = the principal components of the orthogonalised U^ij^
_atom_site.U_equiv_geom_mean_su
Standard uncertainty values (esds) of the U(equiv).
_atom_site.U_iso_or_equiv
Isotropic atomic displacement parameter, or equivalent isotropic atomic displacement parameter, U(equiv), in angstroms squared, calculated from anisotropic atomic displacement parameters.
U(equiv) = (1/3) sum~i~[sum~j~(U^ij^ a*~i~ a*~j~ a~i~ a~j~)]
a = the realspace cell lengths
a* = the reciprocalspace cell lengths
Ref: Fischer, R. X. & Tillmanns, E. (1988). Acta Cryst. C44, 775776.
_atom_site.U_iso_or_equiv_su
Standard uncertainty values (esds) of the U(iso) or U(equiv).
_atom_site.Wyckoff_symbol
The Wyckoff symbol (letter) as listed in the spacegroup section of International Tables for Crystallography, Vol. A (1987).
ATOM_SITE_ANISO
The CATEGORY of data items used to describe the anisotropic thermal parameters of the atomic sites in a crystal structure.
_atom_site_aniso.B_11
(Generic definition) These are the standard anisotropic atomic displacement components in angstroms squared which appear in the structure factor term:
T = exp{1/4 sum_{i} [ sum_{j} (B^{ij} h_{i} h_{j} a*_{i} a*_{j}) ] }
h = the Miller indices a* = the reciprocalspace cell lengths The unique elements of the real symmetric matrix are entered by row.
The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred.
_atom_site_aniso.B_11_su
(Generic definition) These are the standard uncertainty values (SU) for the standard form of the Bij anisotropic atomic displacement components (see _aniso_BIJ. Because these values are TYPE measurand, the su values may in practice be auto generated as part of the Bij calculation.
_atom_site_aniso.B_12
(Generic definition) These are the standard anisotropic atomic displacement components in angstroms squared which appear in the structure factor term:
T = exp{1/4 sum_{i} [ sum_{j} (B^{ij} h_{i} h_{j} a*_{i} a*_{j}) ] }
h = the Miller indices a* = the reciprocalspace cell lengths The unique elements of the real symmetric matrix are entered by row.
The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred.
_atom_site_aniso.B_12_su
(Generic definition) These are the standard uncertainty values (SU) for the standard form of the Bij anisotropic atomic displacement components (see _aniso_BIJ. Because these values are TYPE measurand, the su values may in practice be auto generated as part of the Bij calculation.
_atom_site_aniso.B_13
(Generic definition) These are the standard anisotropic atomic displacement components in angstroms squared which appear in the structure factor term:
T = exp{1/4 sum_{i} [ sum_{j} (B^{ij} h_{i} h_{j} a*_{i} a*_{j}) ] }
h = the Miller indices a* = the reciprocalspace cell lengths The unique elements of the real symmetric matrix are entered by row.
The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred.
_atom_site_aniso.B_13_su
(Generic definition) These are the standard uncertainty values (SU) for the standard form of the Bij anisotropic atomic displacement components (see _aniso_BIJ. Because these values are TYPE measurand, the su values may in practice be auto generated as part of the Bij calculation.
_atom_site_aniso.B_22
(Generic definition) These are the standard anisotropic atomic displacement components in angstroms squared which appear in the structure factor term:
T = exp{1/4 sum_{i} [ sum_{j} (B^{ij} h_{i} h_{j} a*_{i} a*_{j}) ] }
h = the Miller indices a* = the reciprocalspace cell lengths The unique elements of the real symmetric matrix are entered by row.
The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred.
_atom_site_aniso.B_22_su
(Generic definition) These are the standard uncertainty values (SU) for the standard form of the Bij anisotropic atomic displacement components (see _aniso_BIJ. Because these values are TYPE measurand, the su values may in practice be auto generated as part of the Bij calculation.
_atom_site_aniso.B_23
(Generic definition) These are the standard anisotropic atomic displacement components in angstroms squared which appear in the structure factor term:
T = exp{1/4 sum_{i} [ sum_{j} (B^{ij} h_{i} h_{j} a*_{i} a*_{j}) ] }
h = the Miller indices a* = the reciprocalspace cell lengths The unique elements of the real symmetric matrix are entered by row.
The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred.
_atom_site_aniso.B_23_su
(Generic definition) These are the standard uncertainty values (SU) for the standard form of the Bij anisotropic atomic displacement components (see _aniso_BIJ. Because these values are TYPE measurand, the su values may in practice be auto generated as part of the Bij calculation.
_atom_site_aniso.B_33
(Generic definition) These are the standard anisotropic atomic displacement components in angstroms squared which appear in the structure factor term:
T = exp{1/4 sum_{i} [ sum_{j} (B^{ij} h_{i} h_{j} a*_{i} a*_{j}) ] }
h = the Miller indices a* = the reciprocalspace cell lengths The unique elements of the real symmetric matrix are entered by row.
The IUCr Commission on Nomenclature recommends against the use of B for reporting atomic displacement parameters. U, being directly proportional to B, is preferred.
_atom_site_aniso.B_33_su
(Generic definition) These are the standard uncertainty values (SU) for the standard form of the Bij anisotropic atomic displacement components (see _aniso_BIJ. Because these values are TYPE measurand, the su values may in practice be auto generated as part of the Bij calculation.
_atom_site_aniso.label•
Anisotropic atomic displacement parameters are usually looped in a separate list. If this is the case, this code must match the _atom_site_label of the associated atom in the atom coordinate list and conform with the same rules described in _atom_site.label.
_atom_site_aniso.matrix_B
The symmetric anisotropic atomic displacement matrix B.
_atom_site_aniso.matrix_U
The symmetric anisotropic atomic displacement matrix U.
_atom_site_aniso.ratio
Ratio of the maximum to minimum eigenvalues of the atomic displacement (thermal) ellipsoids.
_atom_site_aniso.type_symbol
This _atom_type.symbol code links the anisotropic atom parameters to the atom type data associated with this site and must match one of the _atom_type.symbol codes in this list.
_atom_site_aniso.U_11
(Generic definition) These are the standard anisotropic atomic displacement components in angstroms squared which appear in the structure factor term:
T = exp{2pi^2^ sum~i~ [sum~j~ (U^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }
h = the Miller indices
a* = the reciprocalspace cell lengths
The unique elements of the real symmetric matrix are entered by row.
_atom_site_aniso.U_11_su
(Generic definition) These are the standard uncertainty values (SU) for the standard form of the Uij anisotropic atomic displacement components (see _aniso_UIJ. Because these values are TYPE measurand, the su values may in practice be auto generated as part of the Uij calculation.
_atom_site_aniso.U_12
(Generic definition) These are the standard anisotropic atomic displacement components in angstroms squared which appear in the structure factor term:
T = exp{2pi^2^ sum~i~ [sum~j~ (U^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }
h = the Miller indices
a* = the reciprocalspace cell lengths
The unique elements of the real symmetric matrix are entered by row.
_atom_site_aniso.U_12_su
(Generic definition) These are the standard uncertainty values (SU) for the standard form of the Uij anisotropic atomic displacement components (see _aniso_UIJ. Because these values are TYPE measurand, the su values may in practice be auto generated as part of the Uij calculation.
_atom_site_aniso.U_13
(Generic definition) These are the standard anisotropic atomic displacement components in angstroms squared which appear in the structure factor term:
T = exp{2pi^2^ sum~i~ [sum~j~ (U^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }
h = the Miller indices
a* = the reciprocalspace cell lengths
The unique elements of the real symmetric matrix are entered by row.
_atom_site_aniso.U_13_su
(Generic definition) These are the standard uncertainty values (SU) for the standard form of the Uij anisotropic atomic displacement components (see _aniso_UIJ. Because these values are TYPE measurand, the su values may in practice be auto generated as part of the Uij calculation.
_atom_site_aniso.U_22
(Generic definition) These are the standard anisotropic atomic displacement components in angstroms squared which appear in the structure factor term:
T = exp{2pi^2^ sum~i~ [sum~j~ (U^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }
h = the Miller indices
a* = the reciprocalspace cell lengths
The unique elements of the real symmetric matrix are entered by row.
_atom_site_aniso.U_22_su
(Generic definition) These are the standard uncertainty values (SU) for the standard form of the Uij anisotropic atomic displacement components (see _aniso_UIJ. Because these values are TYPE measurand, the su values may in practice be auto generated as part of the Uij calculation.
_atom_site_aniso.U_23
(Generic definition) These are the standard anisotropic atomic displacement components in angstroms squared which appear in the structure factor term:
T = exp{2pi^2^ sum~i~ [sum~j~ (U^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }
h = the Miller indices
a* = the reciprocalspace cell lengths
The unique elements of the real symmetric matrix are entered by row.
_atom_site_aniso.U_23_su
(Generic definition) These are the standard uncertainty values (SU) for the standard form of the Uij anisotropic atomic displacement components (see _aniso_UIJ. Because these values are TYPE measurand, the su values may in practice be auto generated as part of the Uij calculation.
_atom_site_aniso.U_33
(Generic definition) These are the standard anisotropic atomic displacement components in angstroms squared which appear in the structure factor term:
T = exp{2pi^2^ sum~i~ [sum~j~ (U^ij^ h~i~ h~j~ a*~i~ a*~j~) ] }
h = the Miller indices
a* = the reciprocalspace cell lengths
The unique elements of the real symmetric matrix are entered by row.
_atom_site_aniso.U_33_su
(Generic definition) These are the standard uncertainty values (SU) for the standard form of the Uij anisotropic atomic displacement components (see _aniso_UIJ. Because these values are TYPE measurand, the su values may in practice be auto generated as part of the Uij calculation.
ATOM_SITES
The CATEGORY of data items used to describe information which applies to all atom sites in a crystal structure.
_atom_sites.solution_hydrogens
Codes which identify the methods used to locate the initial atom sites. The *_primary code identifies how the first atom sites were determined; the *_secondary code identifies how the remaining nonhydrogen sites were located; and the *_hydrogens code identifies how the hydrogen sites were located.
Ref: Sheldrick, G. M., Hauptman, H. A., Weeks, C. M.,
Miller, R. and Us\'on, I. (2001). Ab initio phasing.
In International Tables for Crystallography,
Vol. F. Crystallography of biological macromolecules,
edited by M. G. Rossmann and E. Arnold, ch. 16.1.
Dordrecht: Kluwer Academic Publishers.
_atom_sites.solution_primary
Codes which identify the methods used to locate the initial atom sites. The *_primary code identifies how the first atom sites were determined; the *_secondary code identifies how the remaining nonhydrogen sites were located; and the *_hydrogens code identifies how the hydrogen sites were located.
Ref: Sheldrick, G. M., Hauptman, H. A., Weeks, C. M.,
Miller, R. and Us\'on, I. (2001). Ab initio phasing.
In International Tables for Crystallography,
Vol. F. Crystallography of biological macromolecules,
edited by M. G. Rossmann and E. Arnold, ch. 16.1.
Dordrecht: Kluwer Academic Publishers.
_atom_sites.solution_secondary
Codes which identify the methods used to locate the initial atom sites. The *_primary code identifies how the first atom sites were determined; the *_secondary code identifies how the remaining nonhydrogen sites were located; and the *_hydrogens code identifies how the hydrogen sites were located.
Ref: Sheldrick, G. M., Hauptman, H. A., Weeks, C. M.,
Miller, R. and Us\'on, I. (2001). Ab initio phasing.
In International Tables for Crystallography,
Vol. F. Crystallography of biological macromolecules,
edited by M. G. Rossmann and E. Arnold, ch. 16.1.
Dordrecht: Kluwer Academic Publishers.
_atom_sites.special_details
Information about atomic coordinates not coded elsewhere in the CIF.
ATOM_SITES_CARTN_TRANSFORM
The CATEGORY of data items used to describe the matrix elements used to transform Cartesion coordinates into fractional coordinates of all atom sites in a crystal structure.
_atom_sites_Cartn_transform.axes
Description of the relative alignment of the crystal cell axes to the Cartesian orthogonal axes as applied in the transformation matrix _atom_sites_Cartn_transform.matrix.
_atom_sites_Cartn_transform.mat_11
(Generic definition) Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes. The 3x1 translation is defined in _atom_sites_Cartn_transform.vector.
x' 11 12 13 x  1  ( y' )Cartesian = mat21 22 23 * ( y )fractional + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_Cartn_transform.mat_12
(Generic definition) Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes. The 3x1 translation is defined in _atom_sites_Cartn_transform.vector.
x' 11 12 13 x  1  ( y' )Cartesian = mat21 22 23 * ( y )fractional + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_Cartn_transform.mat_13
(Generic definition) Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes. The 3x1 translation is defined in _atom_sites_Cartn_transform.vector.
x' 11 12 13 x  1  ( y' )Cartesian = mat21 22 23 * ( y )fractional + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_Cartn_transform.mat_21
(Generic definition) Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes. The 3x1 translation is defined in _atom_sites_Cartn_transform.vector.
x' 11 12 13 x  1  ( y' )Cartesian = mat21 22 23 * ( y )fractional + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_Cartn_transform.mat_22
(Generic definition) Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes. The 3x1 translation is defined in _atom_sites_Cartn_transform.vector.
x' 11 12 13 x  1  ( y' )Cartesian = mat21 22 23 * ( y )fractional + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_Cartn_transform.mat_23
(Generic definition) Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes. The 3x1 translation is defined in _atom_sites_Cartn_transform.vector.
x' 11 12 13 x  1  ( y' )Cartesian = mat21 22 23 * ( y )fractional + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_Cartn_transform.mat_31
(Generic definition) Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes. The 3x1 translation is defined in _atom_sites_Cartn_transform.vector.
x' 11 12 13 x  1  ( y' )Cartesian = mat21 22 23 * ( y )fractional + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_Cartn_transform.mat_32
(Generic definition) Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes. The 3x1 translation is defined in _atom_sites_Cartn_transform.vector.
x' 11 12 13 x  1  ( y' )Cartesian = mat21 22 23 * ( y )fractional + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_Cartn_transform.mat_33
(Generic definition) Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes. The 3x1 translation is defined in _atom_sites_Cartn_transform.vector.
x' 11 12 13 x  1  ( y' )Cartesian = mat21 22 23 * ( y )fractional + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_Cartn_transform.matrix
Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes. The 3 x 1 translation is defined in _atom_sites_Cartn_transform.vector.
x' 11 12 13 x  1 
( y' ) Cartesian = 21 22 23 * ( y ) fractional + v 2 
z' 31 32 33 z  3 
The default transformation matrix uses Rollet's axial
assignments with cell vectors a,b,c aligned with orthogonal
axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_Cartn_transform.vec_1
(Generic definition) Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes. The 3x1 translation is defined in _atom_sites_Cartn_transform.vector.
x' 11 12 13 x  1  ( y' )Cartesian = mat21 22 23 * ( y )fractional + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_Cartn_transform.vec_2
(Generic definition) Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes. The 3x1 translation is defined in _atom_sites_Cartn_transform.vector.
x' 11 12 13 x  1  ( y' )Cartesian = mat21 22 23 * ( y )fractional + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_Cartn_transform.vec_3
(Generic definition) Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes. The 3x1 translation is defined in _atom_sites_Cartn_transform.vector.
x' 11 12 13 x  1  ( y' )Cartesian = mat21 22 23 * ( y )fractional + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_Cartn_transform.vector
The 3x1 translation is used with _atom_sites_Cartn_transform.matrix used to transform fractional coordinates to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_Cartn_transform.axes.
ATOM_SITES_FRACT_TRANSFORM
The CATEGORY of data items used to describe the matrix elements used to transform Cartesion coordinates into fractional coordinates of all atom sites in a crystal structure.
_atom_sites_fract_transform.axes
Description of the relative alignment of the crystal cell axes to the Cartesian orthogonal axes as applied in the transformation matrix _atom_sites_fract_transform.matrix.
_atom_sites_fract_transform.mat_11
(Generic definition) Matrix used to transform Cartesian coordinates in the ATOM_SITE category to fractional coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes. The 3x1 translation is defined in _atom_sites_fract_transform.vector.
x' 11 12 13 x  1  ( y' )fractional = mat21 22 23 * ( y )Cartesian + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_fract_transform.mat_12
(Generic definition) Matrix used to transform Cartesian coordinates in the ATOM_SITE category to fractional coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes. The 3x1 translation is defined in _atom_sites_fract_transform.vector.
x' 11 12 13 x  1  ( y' )fractional = mat21 22 23 * ( y )Cartesian + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_fract_transform.mat_13
(Generic definition) Matrix used to transform Cartesian coordinates in the ATOM_SITE category to fractional coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes. The 3x1 translation is defined in _atom_sites_fract_transform.vector.
x' 11 12 13 x  1  ( y' )fractional = mat21 22 23 * ( y )Cartesian + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_fract_transform.mat_21
(Generic definition) Matrix used to transform Cartesian coordinates in the ATOM_SITE category to fractional coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes. The 3x1 translation is defined in _atom_sites_fract_transform.vector.
x' 11 12 13 x  1  ( y' )fractional = mat21 22 23 * ( y )Cartesian + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_fract_transform.mat_22
(Generic definition) Matrix used to transform Cartesian coordinates in the ATOM_SITE category to fractional coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes. The 3x1 translation is defined in _atom_sites_fract_transform.vector.
x' 11 12 13 x  1  ( y' )fractional = mat21 22 23 * ( y )Cartesian + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_fract_transform.mat_23
(Generic definition) Matrix used to transform Cartesian coordinates in the ATOM_SITE category to fractional coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes. The 3x1 translation is defined in _atom_sites_fract_transform.vector.
x' 11 12 13 x  1  ( y' )fractional = mat21 22 23 * ( y )Cartesian + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_fract_transform.mat_31
(Generic definition) Matrix used to transform Cartesian coordinates in the ATOM_SITE category to fractional coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes. The 3x1 translation is defined in _atom_sites_fract_transform.vector.
x' 11 12 13 x  1  ( y' )fractional = mat21 22 23 * ( y )Cartesian + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_fract_transform.mat_32
(Generic definition) Matrix used to transform Cartesian coordinates in the ATOM_SITE category to fractional coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes. The 3x1 translation is defined in _atom_sites_fract_transform.vector.
x' 11 12 13 x  1  ( y' )fractional = mat21 22 23 * ( y )Cartesian + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_fract_transform.mat_33
(Generic definition) Matrix used to transform Cartesian coordinates in the ATOM_SITE category to fractional coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes. The 3x1 translation is defined in _atom_sites_fract_transform.vector.
x' 11 12 13 x  1  ( y' )fractional = mat21 22 23 * ( y )Cartesian + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_fract_transform.matrix
Matrix used to transform fractional coordinates in the ATOM_SITE category to Cartesian coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes. The 3 x 1 translation is defined in _atom_sites_fract_transform.vector.
x' 11 12 13 x  1 
( y' )fractional = mat 21 22 23 * ( y ) Cartesian + vec 2 
z' 31 32 33 z  3 
The default transformation matrix uses Rollet's axial
assignments with cell vectors a,b,c aligned with orthogonal
axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_fract_transform.vec_1
(Generic definition) Matrix used to transform Cartesian coordinates in the ATOM_SITE category to fractional coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes. The 3x1 translation is defined in _atom_sites_fract_transform.vector.
x' 11 12 13 x  1  ( y' )fractional = mat21 22 23 * ( y )Cartesian + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_fract_transform.vec_2
(Generic definition) Matrix used to transform Cartesian coordinates in the ATOM_SITE category to fractional coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes. The 3x1 translation is defined in _atom_sites_fract_transform.vector.
x' 11 12 13 x  1  ( y' )fractional = mat21 22 23 * ( y )Cartesian + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_fract_transform.vec_3
(Generic definition) Matrix used to transform Cartesian coordinates in the ATOM_SITE category to fractional coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes. The 3x1 translation is defined in _atom_sites_fract_transform.vector.
x' 11 12 13 x  1  ( y' )fractional = mat21 22 23 * ( y )Cartesian + vec 2  z' 31 32 33 z  3 
The default transformation matrix uses Rollet’s axial assignments with cell vectors a,b,c aligned with orthogonal axes X,Y,Z so that cZ and b in plane YZ.
_atom_sites_fract_transform.vector
The 3x1 translation is used with _atom_sites_fract_transform.matrix used to transform Cartesian coordinates to fractional coordinates. The axial alignments of this transformation are described in _atom_sites_fract_transform.axes.
ATOM_TYPE
The CATEGORY of data items used to describe atomic type information used in crystallographic structure studies.
_atom_type.analytical_mass_percent
Mass percentage of this atom type derived from chemical analysis.
_atom_type.atomic_mass
Mass of this atom type.
_atom_type.atomic_number
Atomic number of this atom type.
_atom_type.description
A description of the atom(s) designated by this atom type. In most cases this will be the element name and oxidation state of a single atom species. For disordered or nonstoichiometric structures it will describe a combination of atom species.
_atom_type.display_colour
The display colour assigned to this atom type. Note that the possible colours are enumerated in the display_colour list category of items.
_atom_type.electron_count
Number of electrons in this atom type.
_atom_type.element_symbol
Element symbol for of this atom type. The default value is extracted from the iontoelement enumeration_default list using the index value of atom_type.symbol.
_atom_type.key
Value is a unique key to a set of ATOM_TYPE items in a looped list.
_atom_type.number_in_cell
Total number of atoms of this atom type in the unit cell.
_atom_type.oxidation_number
Formal oxidation state of this atom type in the structure.
_atom_type.radius_bond
The effective intramolecular bonding radius of this atom type.
_atom_type.radius_contact
The effective intermolecular bonding radius of this atom type.
_atom_type.symbol•
The identity of the atom specie(s) representing this atom type. Normally this code is the element symbol followed by the charge if there is one. The symbol may be composed of any character except an underline or a blank, with the proviso that digits designate an oxidation state and must be followed by a + or  character.
ATOM_TYPE_SCAT
The CATEGORY of data items used to describe atomic scattering information used in crystallographic structure studies.
_atom_type_scat.Cromer_Mann_a1
(Generic definition) The set of data items used to define CromerMann coefficients for generation of Xray scattering factors.
Ref: International Tables for Xray Crystallography, Vol. IV (1974) Table 2.2B or International Tables for Crystallography, Vol. C (1991) Tables 6.1.1.4 and 6.1.1.5
_atom_type_scat.Cromer_Mann_a2
(Generic definition) The set of data items used to define CromerMann coefficients for generation of Xray scattering factors.
Ref: International Tables for Xray Crystallography, Vol. IV (1974) Table 2.2B or International Tables for Crystallography, Vol. C (1991) Tables 6.1.1.4 and 6.1.1.5
_atom_type_scat.Cromer_Mann_a3
(Generic definition) The set of data items used to define CromerMann coefficients for generation of Xray scattering factors.
Ref: International Tables for Xray Crystallography, Vol. IV (1974) Table 2.2B or International Tables for Crystallography, Vol. C (1991) Tables 6.1.1.4 and 6.1.1.5
_atom_type_scat.Cromer_Mann_a4
(Generic definition) The set of data items used to define CromerMann coefficients for generation of Xray scattering factors.
Ref: International Tables for Xray Crystallography, Vol. IV (1974) Table 2.2B or International Tables for Crystallography, Vol. C (1991) Tables 6.1.1.4 and 6.1.1.5
_atom_type_scat.Cromer_Mann_b1
(Generic definition) The set of data items used to define CromerMann coefficients for generation of Xray scattering factors.
Ref: International Tables for Xray Crystallography, Vol. IV (1974) Table 2.2B or International Tables for Crystallography, Vol. C (1991) Tables 6.1.1.4 and 6.1.1.5
_atom_type_scat.Cromer_Mann_b2
(Generic definition) The set of data items used to define CromerMann coefficients for generation of Xray scattering factors.
Ref: International Tables for Xray Crystallography, Vol. IV (1974) Table 2.2B or International Tables for Crystallography, Vol. C (1991) Tables 6.1.1.4 and 6.1.1.5
_atom_type_scat.Cromer_Mann_b3
(Generic definition) The set of data items used to define CromerMann coefficients for generation of Xray scattering factors.
Ref: International Tables for Xray Crystallography, Vol. IV (1974) Table 2.2B or International Tables for Crystallography, Vol. C (1991) Tables 6.1.1.4 and 6.1.1.5
_atom_type_scat.Cromer_Mann_b4
(Generic definition) The set of data items used to define CromerMann coefficients for generation of Xray scattering factors.
Ref: International Tables for Xray Crystallography, Vol. IV (1974) Table 2.2B or International Tables for Crystallography, Vol. C (1991) Tables 6.1.1.4 and 6.1.1.5
_atom_type_scat.Cromer_Mann_c
(Generic definition) The set of data items used to define CromerMann coefficients for generation of Xray scattering factors.
Ref: International Tables for Xray Crystallography, Vol. IV (1974) Table 2.2B or International Tables for Crystallography, Vol. C (1991) Tables 6.1.1.4 and 6.1.1.5
_atom_type_scat.Cromer_Mann_coeffs
The set of CromerMann coefficients for generating Xray scattering factors. [ a1, b1, a2, b2, a3, b3, a4, b4, c] Ref: International Tables for Crystallography, Vol. C (1991) Table 6.1.1.4
_atom_type_scat.dispersion
The anomalous dispersion scattering factor in its complex form for this atom type and radiation by _diffrn_radiation_wavelength.value
_atom_type_scat.dispersion_imag
The imaginary component of the anomalous dispersion scattering factors for this atom type and radiation by _diffrn_radiation_wavelength.value
_atom_type_scat.dispersion_imag_cu
The imaginary component of the anomalous dispersion scattering factors for this atom type and Cu K alpha radiation
_atom_type_scat.dispersion_imag_mo
The imaginary component of the anomalous dispersion scattering factors for this atom type and Mo K alpha radiation
_atom_type_scat.dispersion_real
The real component of the anomalous dispersion scattering factors for this atom type and radiation by _diffrn_radiation_wavelength.value
_atom_type_scat.dispersion_real_cu
The real component of the anomalous dispersion scattering factors for this atom type and Cu K alpha radiation
_atom_type_scat.dispersion_real_mo
The real component of the anomalous dispersion scattering factors for this atom type and Mo K alpha radiation
_atom_type_scat.dispersion_source
Reference to source of real and imaginary dispersion corrections for scattering factors used for this atom type.
_atom_type_scat.hi_ang_Fox_c0
(Generic definition) The set of data items used to define Fox et al. coefficients for generation of high angle (s >2.0) Xray scattering factors.
Ref: International Tables for Crystallography, Vol. C (1991) Table 6.1.1.5
_atom_type_scat.hi_ang_Fox_c1
(Generic definition) The set of data items used to define Fox et al. coefficients for generation of high angle (s >2.0) Xray scattering factors.
Ref: International Tables for Crystallography, Vol. C (1991) Table 6.1.1.5
_atom_type_scat.hi_ang_Fox_c2
(Generic definition) The set of data items used to define Fox et al. coefficients for generation of high angle (s >2.0) Xray scattering factors.
Ref: International Tables for Crystallography, Vol. C (1991) Table 6.1.1.5
_atom_type_scat.hi_ang_Fox_c3
(Generic definition) The set of data items used to define Fox et al. coefficients for generation of high angle (s >2.0) Xray scattering factors.
Ref: International Tables for Crystallography, Vol. C (1991) Table 6.1.1.5
_atom_type_scat.hi_ang_Fox_coeffs
The set of Fox et al. coefficients for generating high angle Xray scattering factors. [ c0, c1, c2, c3 ] Ref: International Tables for Crystallography, Vol. C (1991) Table 6.1.1.5
_atom_type_scat.length_neutron
The bound coherent scattering length for the atom type at the isotopic composition used for the diffraction experiment.
_atom_type_scat.source
Reference to source of scattering factors used for this atom type.
_atom_type_scat.symbol•
The identity of the atom specie(s) representing this atom type. See _atom_type.symbol for further details.
_atom_type_scat.versus_stol_list
List of scattering factors as a function of sin theta on lambda. List has the form [<stol value>:'<scatfac>', ….] in increments of 0.01, increasing from 0.0.
REFINE
The CATEGORY of data items used to specify information about the refinement of the structural model.
_refine.special_details
Details of the refinement not specified by other data items.
REFINE_DIFF
The CATEGORY of data items which specify the electron density limits in a difference Fourier map after the structure has been refined. The rms value is with respect to the arithmetic mean density, and is derived from summations over each grid point in the asymmetric unit of the cell.
_refine_diff.density_max
Maximum density value in a difference Fourier map.
_refine_diff.density_max_su
Standard Uncertainty of the Maximum density value in a difference Fourier map.
_refine_diff.density_min
Miniumum density value in a difference Fourier map.
_refine_diff.density_min_su
Standard Uncertainty of the Miniumum density value in a difference Fourier map.
_refine_diff.density_rms
Root mean square density value in a difference Fourier map. This value is measured with respect to the arithmetic mean density and is derived from summations over each grid point in the asymmetric unit of the cell. This quantity is useful for assessing the significance of *_min and *_max values, and also for defining suitable contour levels.
_refine_diff.density_rms_su
Standard Uncertainty of the Root mean square density value in a difference Fourier map.
REFINE_LS
The CATEGORY of data items used to specify information about the refinement of the structural model.
_refine_ls.abs_structure_details
Details on the absolute structure and how it was determined.
_refine_ls.abs_structure_Flack
The measure of absolute structure as defined by Flack (1983). For centrosymmetric structures, the only permitted value, if the data name is present, is inapplicable, represented by . . For noncentrosymmetric structures, the value must lie in the 99.97% Gaussian confidence interval 3u =< x =< 1 + 3u and a standard uncertainty (e.s.d.) u must be supplied. The _enumeration.range of 0.0:1.0 is correctly interpreted as meaning (0.0  3u) =< x =< (1.0 + 3u). Ref: Flack, H. D. (1983). Acta Cryst. A39, 876881.
_refine_ls.abs_structure_Flack_su
Standard Uncertainty of the The measure of absolute structure as defined by Flack (1983).
_refine_ls.abs_structure_Rogers
The measure of absolute structure as defined by Rogers (1981). The value must lie in the 99.97% Gaussian confidence interval 1 3u =< \h =< 1 + 3u and a standard uncertainty (e.s.d.) u must be supplied. The _enumeration.range of 1.0:1.0 is correctly interpreted as meaning (1.0  3u) =< \h =< (1.0 + 3u). Ref: Rogers, D. (1981). Acta Cryst. A37, 734741.
_refine_ls.abs_structure_Rogers_su
Standard Uncertainty of the The measure of absolute structure as defined by Rogers (1981).
_refine_ls.d_res_high
Highest resolution for the reflections used in refinement. This corresponds to the smallest interpanar d value.
_refine_ls.d_res_low
Lowest resolution for the reflections used in refinement. This corresponds to the largest interpanar d value.
_refine_ls.extinction_coef
The extinction coefficient used to calculate the correction factor applied to the structurefactor data. The nature of the extinction coefficient is given in the definitions of _refine_ls.extinction_expression and _refine_ls.extinction_method. For the Zachariasen method it is the r* value; for the BeckerCoppens type 1 isotropic method it is the g value. For BeckerCoppens type 2 isotropic corrections it is the rho value. Note that the magnitude of these values is usually of the order of 10000. Ref: Becker, P. J. & Coppens, P. (1974). Acta Cryst. A30, 129147, 148153. Zachariasen, W. H. (1967). Acta Cryst. 23, 558564. Larson, A. C. (1967). Acta Cryst. 23, 664665.
_refine_ls.extinction_coef_su
Standard Uncertainty of the extinction coefficient
_refine_ls.extinction_expression
Description of or reference to the extinctioncorrection equation used to apply the data item _refine_ls.extinction_coef. This information should be sufficient to reproduce the extinction correction factors applied to the structure factors.
_refine_ls.extinction_method
Description of the extinction correction method applied with the data item _refine_ls.extinction_coef. This description should include information about the correction method, either Becker Coppens or Zachariasen. The latter is sometimes referred to as the Larson method even though it employs Zachariasen’s formula.
The BeckerCoppens procedure is referred to as 'type 1' when
correcting secondary extinction dominated by the mosaic spread;
as 'type 2' when secondary extinction is dominated by particle
size and includes a primary extinction component; and as 'mixed'
when there are types 1 and 2.
For the BeckerCoppens method it is also necessary to set the
mosaic distribution as either 'Gaussian' or 'Lorentzian'; and the
nature of the extinction as 'isotropic' or 'anisotropic'. Note
that if either the 'mixed' or 'anisotropic' corrections are applied
the multiple coefficients cannot be contained in the
_refine_ls.extinction_coef and must be listed in *.special_details.
Ref: Becker, P. J. & Coppens, P. (1974). Acta Cryst. A30, 129153.
Zachariasen, W. H. (1967). Acta Cryst. 23, 558564.
Larson, A. C. (1967). Acta Cryst. 23, 664665.
_refine_ls.F_calc_details
Details concerning the evaluation of the structure factors using the expression given in _refine_ls.F_calc_formula.
_refine_ls.F_calc_formula
Analytical expression used to calculate the structure factors.
_refine_ls.F_calc_precision
Estimate of the precision resulting from the numerical approximations made during the evaluation of the structure factors using the expression _refine_ls.F_calc_formula following the method outlined in _refine_ls.F_calc_details.
_refine_ls.goodness_of_fit_all
Leastsquares goodnessoffit parameter S for all reflections after the final cycle of refinement. Ideally, account should be taken of parameters restrained in the least squares.
{ sum { w [ Y(meas)  Y(calc) ]^2^ } }^1/2^
S = {  }
{ Nref  Nparam }
Y(meas) = the measured coefficients
(see _refine_ls.structure_factor_coef)
Y(calc) = the calculated coefficients
(see _refine_ls.structure_factor_coef)
w = the leastsquares reflection weight
[1/(u^2^)]
u = standard uncertainty
Nref = the number of reflections used in the refinement
Nparam = the number of refined parameters
and the sum is taken over the specified reflections
_refine_ls.goodness_of_fit_all_su
Standard Uncertainty of the Leastsquares goodnessoffit parameter S for all reflections after the final cycle of refinement.
_refine_ls.goodness_of_fit_gt
Leastsquares goodnessoffit parameter S for significantly intense reflections, (i.e. observed reflections with values greaterthan the threshold set in _reflns.threshold_expression), after the final cycle. Ideally, account should be taken of parameters restrained in the leastsquares refinement.
{ sum { w [ Y(meas_gt)  Y(calc) ]^2^ } }^1/2^
S = {  }
{ Nref  Nparam }
Y(meas_gt) = the 'observed' coefficients
(see _refine_ls.structure_factor_coef)
Y(calc) = the calculated coefficients
(see _refine_ls.structure_factor_coef)
w = the leastsquares reflection weight
[1/(u^2^)]
u = standard uncertainty
Nref = the number of reflections used in the refinement
Nparam = the number of refined parameters
and the sum is taken over the specified reflections
_refine_ls.goodness_of_fit_gt_su
Standard Uncertainty of the Leastsquares goodnessoffit parameter S for gt reflections after the final cycle of refinement.
_refine_ls.goodness_of_fit_ref
Leastsquares goodnessoffit parameter S for those reflections included in the final cycle of refinement. Account should be taken of restrained parameters.
{ sum { w [ Y(meas)  Y(calc) ]^2^ } }^1/2^
S = {  }
{ Nref  Nparam }
Y(meas) = the measured coefficients
(see _refine_ls.structure_factor_coef)
Y(calc) = the calculated coefficients
(see _refine_ls.structure_factor_coef)
w = the leastsquares reflection weight
[1/(u^2^)]
u = standard uncertainty
Nref = the number of reflections used in the refinement
Nparam = the number of refined parameters
and the sum is taken over the specified reflections
_refine_ls.hydrogen_treatment
Code identifying how hydrogen atoms were treated in the refinement.
_refine_ls.matrix_type
Code identifying the matrix type used for leastsquares derivatives.
_refine_ls.number_constraints
Number of constrained (nonrefined or dependent) parameters in the leastsquares process. These may be due to symmetry or any other constraint process (e.g. rigidbody refinement). See also _atom_site.constraints and _atom_site.refinement_flags. A general description of constraints may appear in _refine.special_details.
_refine_ls.number_parameters
Number of parameters refined in the leastsquares process. If possible this number should include the restrained parameters. The restrained parameters are distinct from the constrained parameters (where one or more parameters are linearly dependent on the refined value of another). Leastsquares restraints often depend on geometry or energy considerations and this makes their direct contribution to this number, and to the goodnessoffit calculation, difficult to assess.
_refine_ls.number_reflns
Number of unique reflections used in the leastsquares refinement.
_refine_ls.number_reflns_gt
The number of reflections that satisfy the resolution limits established by _refine.ls_d_res_high and _refine.ls_d_res_low and the observation limit established by _reflns.observed_criterion.
_refine_ls.number_restraints
Number of restrained parameters in the leastsquares refinement. These parameters do not directly dependent on another refined parameter. Often restrained parameters involve geometry or energy dependencies. See also _atom_site.constraints and _atom_site.refinement_flags. A description of refinement constraints may appear in _refine.special_details.
_refine_ls.R_factor_all
Residual factor for all reflections satisfying the resolution limits specified by _refine_ls.d_res_high and _refine_ls.d_res_low. This is the conventional R factor. See also wR factor definitions.
sum  F(meas)  F(calc) 
R = 
sum  F(meas) 
F(meas) = the measured structurefactor amplitudes
F(calc) = the calculated structurefactor amplitudes
and the sum is taken over the specified reflections
_refine_ls.R_factor_gt
Residual factor for the reflections judged significantly intense (see _reflns.number_gt and _reflns.threshold_expression) and included in the refinement. The reflections also satisfy the resolution limits specified by _refine_ls.d_res_high and _refine_ls.d_res_low. This is the conventional R factor.
sum  F(meas_gt)  F(calc) 
R = 
sum  F(meas_gt) 
F(meas_gt) = the 'observed' structurefactor amplitudes
F(calc) = the calculated structurefactor amplitudes
and the sum is taken over the specified reflections
_refine_ls.R_Fsqd_factor
Residual factor R(Fsqd), calculated on the squared amplitudes of the measured and calculated structure factors, for significantly intense reflections (satisfying _reflns.threshold_expression) and included in the refinement. The reflections also satisfy the resolution limits specified by _refine_ls.d_res_high and _refine_ls.d_res_low.
sum  F(meas_gt)^2^  F(calc)^2^ 
R(Fsqd) = 
sum F(meas_gt)^2^
F(meas_gt)^2^ = squares of the 'observed' structurefactor
F(calc)^2^ = squares of the calculated structurefactor
and the sum is taken over the specified reflections
_refine_ls.R_I_factor
Residual factor R(I) for significantly intense reflections (satisfying _reflns.threshold_expression) and included in the refinement. This is most often calculated in Rietveld refinements of powder data, where it is referred to as R_{B} or R_{Bragg}.
sum  I(meas_gt)  I(calc) 
R(I) = 
sum  I(meas_gt) 
I(meas_gt) = the net 'observed' intensities
I(calc) = the net calculated intensities
and the sum is taken over the specified reflections
_refine_ls.restrained_S_all
Leastsquares goodnessoffit parameter S' for all reflections after the final cycle of least squares. This parameter explicitly includes the restraints applied in the leastsquares process. See also _refine_ls.goodness_of_fit_all definition.
{sum { w [ Y(meas)  Y(calc) ]^2^ } }^1/2^
{ + sum~r~ { w~r~ [ P(calc)  P(targ) ]^2^ } }
S' = {  }
{ N~ref~ + N~restr~  N~param~ }
Y(meas) = the measured coefficients
(see _refine_ls.structure_factor_coef)
Y(calc) = the calculated coefficients
(see _refine_ls.structure_factor_coef)
w = the leastsquares reflection weight
[1/square of standard uncertainty (e.s.d.)]
P(calc) = the calculated restraint values
P(targ) = the target restraint values
w~r~ = the restraint weight
N~ref~ = the number of reflections used in the refinement
(see _refine_ls.number_reflns)
N~restr~ = the number of restraints
(see _refine_ls.number_restraints)
N~param~ = the number of refined parameters
(see _refine_ls.number_parameters)
sum is taken over the specified reflections
sum~r~ is taken over the restraints
_refine_ls.restrained_S_gt
Leastsquares goodnessoffit parameter S' for significantly intense reflections (satisfying _reflns.threshold_expression) after the final cycle of least squares. This parameter explicitly includes the restraints applied. The expression for S' is given in _refine_ls.restrained_S_all.
{sum { w [ Y(meas_gt)  Y(calc) ]^2^ } }^1/2^
{ + sum~r~ { w~r~ [ P(calc)  P(targ) ]^2^ } }
S' = {  }
{ N~ref~ + N~restr~  N~param~ }
Y(meas_gt) = the 'observed' coefficients
(see _refine_ls.structure_factor_coef)
Y(calc) = the calculated coefficients
(see _refine_ls.structure_factor_coef)
w = the leastsquares reflection weight
[1/square of standard uncertainty (e.s.d.)]
P(calc) = the calculated restraint values
P(targ) = the target restraint values
w~r~ = the restraint weight
N~ref~ = the number of reflections used in the refinement
(see _refine_ls.number_reflns)
N~restr~ = the number of restraints
(see _refine_ls.number_restraints)
N~param~ = the number of refined parameters
(see _refine_ls.number_parameters)
sum is taken over the specified reflections
sum~r~ is taken over the restraints
_refine_ls.shift_over_su_max
The largest ratio of the final leastsquares parameter shift to the final standard uncertainty (s.u., formerly described as estimated standard deviation, e.s.d.).
_refine_ls.shift_over_su_max_lt
Upper limit for the largest ratio of the final ls parameter shift divided by the final standard uncertainty. This item is used when the largest value of the shift divided by the final standard uncertainty is too small to measure.
_refine_ls.shift_over_su_mean
The average ratio of the final leastsquares parameter shift to the final standard uncertainty (s.u., formerly described as estimated standard deviation, e.s.d.).
_refine_ls.shift_over_su_mean_lt
Upper limit for the average ratio of the final ls parameter shift divided by the final standard uncertainty. This item is used when the average value of the shift divided by the final standard uncertainty is too small to measure.
_refine_ls.structure_factor_coef
Structurefactor coefficient used in the leastsquares process.
_refine_ls.weighting_details
Description of special aspects of the weighting scheme used in the leastsquares refinement. Used to describe the weighting when the value of _refine_ls.weighting_scheme is specified as calc.
_refine_ls.weighting_scheme
General description of the weighting scheme used in the leastsquares. An enumerated code should be contained in this description.
_refine_ls.wR_factor_all
Weighted residual factors for all reflections satisfying the resolution limits specified by _refine_ls.d_res_high and _refine_ls.d_res_low. See also the _refine_ls.R_factor_all definition.
( sum w [ Y(meas)  Y(calc) ]^2^ )^1/2^
wR = (  )
( sum w Y(meas)^2^ )
Y(meas) = the measured amplitude _refine_ls.structure_factor_coef
Y(calc) = the calculated amplitude _refine_ls.structure_factor_coef
w = the leastsquares weight
and the sum is taken over the specified reflections
_refine_ls.wR_factor_gt
Weighted residual factors for significantly intense reflections (satisfying @reflns_threshold_expression) included in the refinement. The reflections must also satisfy the resolution limits established by _refine_ls.d_res_high and _refine_ls.d_res_low.
( sum w [ Y(meas_gt)  Y(calc) ]^2^ )^1/2^
wR = (  )
( sum w Y(meas_gt)^2^ )
Y(meas_gt) = the 'observed' amplitude _refine_ls.structure_factor_coef
Y(calc) = the calculated amplitude _refine_ls.structure_factor_coef
w = the leastsquares weight
and the sum is taken over the specified reflections
_refine_ls.wR_factor_ref
Weighted residual factors for reflections included in the refinement which satisfy the limits specified by _refine_ls.d_res_high and _refine_ls.d_res_low.
( sum w [ Y(meas)  Y(calc) ]^2^ )^1/2^
wR = (  )
( sum w Y(meas)^2^ )
Y(meas) = the measured amplitude _refine_ls.structure_factor_coef
Y(calc) = the calculated amplitude _refine_ls.structure_factor_coef
w = the leastsquares weight
and the sum is taken over the specified reflections
REFINE_LS_CLASS
The CATEGORY of data items used to specify information about the refinement of the structural model.
_refine_ls_class.code•
Code identifying a certain reflection class.
_refine_ls_class.d_res_high
Highest resolution for the reflections in this class. This corresponds to the smallest interpanar d value.
_refine_ls_class.d_res_low
Lowest resolution for the reflections in this class. This corresponds to the largest interpanar d value.
_refine_ls_class.R_factor_all
Residual factor for reflections in this class included in the refinement. See _refine_ls.R_factor_all definition for details.
_refine_ls_class.R_factor_gt
Residual factor for the reflections in this class judged significantly intense (see _reflns.threshold_expression) and included in refinement. See _refine_ls.R_factor_gt for details.
_refine_ls_class.R_Fsqd_factor
Residual factor R(F^{2}) for reflections in this class judged significantly intense (see _reflns.threshold_expression) and included in refinement. See _refine_ls.R_Fsqd_factor for details.
_refine_ls_class.R_I_factor
Residual factor R(I) for reflections in this class judged significantly intense (see _reflns.threshold_expression) and included in refinement. See _refine_ls.R_I_factor for details.
_refine_ls_class.wR_factor_all
Weight residual for all reflections in this class judged significantly intense (see _reflns.threshold_expression) and included in refinement. See _refine_ls.wR_factor_all for details.