Export Data File
Previous  Top  Next

Dialog Box: Export Data File [ File Menu ]

You have the choice of exporting the original (Old) or transformed (New) data. Note that the transformed data is not otherwise saved except in the .ccd file which is written on transformation, although it can be recalculated easily enough.

Most of the import/export formats supported by CRYSCON fall into one of two categories; archival formats and refinement formats. The archival formats, such as CIF, ICSD and CCDC tend to give only basic crystallographic information, including space group, unit cell parameters, atomic coordinates and thermal parameters. The refinement file formats, such as DBWF, SHELX and GSAS generally contain much more information, such as scattering factors, weighting factors and refinement flags. CRYSCON generally cannot provide all this latter information, and it cannot be expected that a refinement-format file written by CRYSCON will be successfully read in by the target refinement program (e.g. DBWF, SHELX or GSAS) without many additions and even some editing of the lines which are written by CRYSCON, since even these lines may contain some refinement-specific data.

Space groups symbols may be written in many ways, for example space group number 116: P-4c2; P -4 c 2; P_-4_c_2; P4-c2. CRYSCON does not generally change the symbol - it is usually exported in the form it was imported or entered. The SgInfo routines used by CRYSCON can interpret many of the variations, but export target program may not be able to interpret some forms, and it may be necessary to edit the space group symbol after exporting a file.

You can convert the type of the temperature factors, e.g. from beta's to U's; and/or you can convert from isotropic to anisotropic and vice versa. Of course not all export formats allow a choice. If the Keep current form radio button is checked, the current temperature factors will be kept, if possible . However, the export format may not support the current form, in which case the temperature factors will be converted to a type which is supported.

The equivalent isotropic temperature factor, if converting from anisotropic to isotropic, will be computed according to the formula:

Beq = 2pi^2 (1/3) Sum(i) Sum(j) U(ij) a*(i) a*(j) A(i) A(j) where a*'s are the reciprocal axis lengths and A's are the direct axis lengths.

If the Remove multiple occupancies box is checked, only a single atom will be written for each site, using the relevant data for the first atom in the list of occupants. If not, in most file formats a new atom will be written for each site occupant - that is, the number of atoms in the export file will be larger than the number of sites listed by CRYSCON.

Note that when different input atoms are consolidated during a transformation, for example super- to sub-cell, CRYSCON does not attempt to combine the two sets of occupancies; it simply takes the list of occupants from the first atom generated.