CIF Data Importer

Information about CIF format required

The CIF data importer can only be used on CIF files which comply with certain formatting rules, described here.

Multiple CIF files can be selected for import if the structures to be imported are not in a single file (although for submission it would be preferred if these could be compiled into a single CIF file). Files with extension .cif and .txt can be selected for import.

Different crystal structures start with a line which starts with 'data_' (with the exception of the 'data_global' and 'data_publication_text' lines) and end with '#==END' (although if this label is missing the import will still work). The suffix following 'data_' is taken to be the default name for the structure (e.g. data_NameInCIFfile), but an alternative name can be input if desired.

The following properties are required for the crystallographic data imported from the CIF file to be valid (the label from the CIF file is given in brackets):

• Chemical formula (_chemical_formula_moiety or _chemical_formula_sum)
• Formula Mass (_chemical_formula_weight)
• Crystal system (_symmetry_cell_setting)
• a/Å (_cell_length_a)
• b/Å (_cell_length_b)
• c/Å (_cell_length_c)
• alpha/° (_cell_angle_alpha)
• beta/° (_cell_angle_beta)
• gamma/° (_cell_angle_gamma)
• Unit cell volume/Å (_cell_volume)
• Temperature/K (_cell_measurement_temperature)
• Space group (_symmetry_space_group_name_H-M or _space_group_name_H-M_alt)
• No. of formula units per unit cell, Z (_cell_formula_units_Z)               

At least one of the following properties are required for the crystallographic data imported from the CIF file to be valid:

• No. of reflections measured (_diffrn_reflns_number)
• No. of independent reflections (_reflns_number_total)
• R_int (_diffrn_reflns_av_R_equivalents)               

At least one of the following properties are required for the crystallographic data imported from the CIF file to be valid (note that we assume that '_reflns_threshold_expression' contains a value of '>2sigma(I)' or equivalent):

• Final R₁ values (I > 2sigma(I)) (_refine_ls_R_factor_gt)
• Final wR(F²) values (I > 2sigma(I)) (_refine_ls_wR_factor_gt)
• Final R₁ values (all data) (_refine_ls_R_factor_all)
• Final wR(F²) values (all data) (_refine_ls_wR_factor_ref)               

The following properties can optionally be added:

• Absorption coefficient, mu/mm (_exptl_absorpt_coefficient_mu)
• Radiation type (_diffrn_radiation_type)
• Goodness of fit on F² (_refine_ls_goodness_of_fit_ref)
• Flack parameter (_refine_ls_abs_structure_Flack)
• Rogers parameter (_refine_ls_abs_structure_Rogers)
• CCDC number (_database_code_depnum_ccdc_archive)               

In general, the appropriate property values are simply extracted from the CIF file and inserted into the article with no processing. However, the following exceptions apply:

• Chemical formula (from the _chemical_formula_moiety or _chemical_formula_sum) has spaces removed from within it, commas replaced by the a special bullet character and numbers which don't immediately preceed a ( or [ character turned into subscripts .            
• Radiation type: the string '\a' is replaced by an alpha symbol
• Space groups: non-numeric characters are italicised, spaces are deleted, and hyphens before integers are turned into overbars (using the field function)