DIRDIF - CRYSDA

CRSYDA and the CRYSIN crystal data file

The DIRDIF program CRYSDA reads free format from a CRYSIN file, and/or from a combination of other input possibilities (eg preexisting CRYSDA files, name.INS, name.RES, name.CIF or keyboard) and produces a CRYSDA file which contains the input crystal data as well as a list of related data such as cell volume, calculated density, tables of scattering factors, etc. The CRYSDA file is needed by every DIRDIF job.

Under certain conditions the user may supply the crystal data manually at the terminal.

When during the crystal structure analysis you wish to alter the cell contents or the spacegroup, it is necessary to rerun program CRYSDA (input either the altered CRYSIN file, or the original CRYSDA file and you will be asked to change the data).

The CRYSIN file contains the following records, each record containing a keyword followed by data:

 
   CRYSIN  CCODE                                                (header)
   TITLE   any user supplied information                 (to be printed)
   CELL    a  b  c  alpha beta gamma                  (Angstrom, degree)
   CELLSD  esd's                                           (six numbers)
   SPGR    e.g. P 1  or P -1  or P 21 21 21 or R -3     (different axial
                                   directions are separated by blank(s))
   FORMUL  At1 Nr1 At2 Nr2 At3 Nr3 ......          (continue if needed:)
           At6 Nr6 At7 Nr7 At8 Nr8 ......        (max 10 kinds of atoms)
                      (Ati = chemical symbol, Nri = number of atoms Ati)
                 (e.g. soda Na2CO3.10H2O: FORMUL NA 2 C 1 O 3 H 20 O 10)
   Z       number of FORMUL units per cell
                                     ( Note: cell contents = Z * FORMUL)
   WAVE    Cu  or Mo  or  Fe  or  Ag  or  Cr
   END