Crystals Primer

Chapter 4: Basic Data Input

4.1: Start up

CRYSTALS has powerful reflection processing features, described in the Reference Manual. A simplified input is available if the user knows the unit cell, space group, molecular formula and has a file (e.g. REFLECTIONS.DAT) containing reflections in the form h, k, l, Fsq, Sigma(Fsq), one per line.
 

      !\QUICKSTART
      !CELL         4.05 11.74 24.80
      !SPACEGROUP   P b c n
      !CONTENT      C 13 H 8 O I 2
      !DATA         1.5418       I
      !FILE         CRDIR:REFLECTIONS.DAT
      !FORMAT       (3F4, 2X, 2F8.2)
      !END
      !\LIST 28
      !MINIMA       RATIO=2.5
      !END

Use QUICKSTART for normal situations. This command requires minimal user input, and sets up the basic data lists in the data base. See the manual for a description of the lists created, and how to deal with complicated cases. Permitted reflection data types are Fo, Fsquare, and I. The Lp correction for 4 circle geometry is applied if the type is I. LIST 28 sets the minimum value of I/sigma(I) to be used in calculations.
 
\SCRIPT CADQUICK
 
\SCRIPT CADSLOW

These SCRIPTS takes as input the files produced by the CAD4 data processing program RC93 (or RC85).