X-GEN Manual, Section 5 XASCA (ascii SCALEPACK-style output) File Formats

XASCA is an ascii file written in the style of the SCALEPACK ".sca" file, with the Friedel-separated merged. This file is output from the "makemu" and "scalem" applications of X-GEN. It is always written out along with the file XSCA, which is a SCALEPACK-style output file with the Friedel-mates merged. The format of a reflection line in the XASCA file is: 

 h k l I+ sigma(I+) I- sigma(I-)
in format " %3d %3d %3d %7.1f %7.1f %7.1f %7.1f"
for all reflections for which the intensity is measured and both Friedel mates are present. If the reflection is centric, only I and sigma are output in the I+, sigma(I+) slots. If the reflection is acentric but only I+ has been measured, then I- will be set to 0 and sigma(I-) will be set to -1. If the reflection is acentric but only I- has been measured, then I+ will be set to 0 and sigma(I+) will be set to -1.

The file begins with a three-line header. The first line contains a 1 and the second contains the flag value -985, both in format %5d. The third line contains the unit cell and the spacegroup in the following style:

 a  b  c  alpha  beta  gamma spgrp
in format " %9.3f %9.3f %9.3f %9.3f %9.3f %4s",
where the spacegroup is written in a lower-case, no-subscript form. Thus spacegroup P2(1)2(1)2(1) appears as p212121. This provides an unambiguous rendering for all noncentrosymmetric space groups; whether it works as unambiguously for all centrosymmetric space groups is unclear.

Accordingly the first four lines in a typical file look like

    1
 -985
   111.268   111.268   176.543    90.000    90.000   120.000 p31
   0   2   5   260.6     7.4
and after additional lines showing only centric reflections, the acentrics look like 
   1   9  20    58.7    29.7    78.3    32.3
   1   9  21  2928.6    39.7  3035.0    39.5

Reflections will normally be sorted with L varying fastest, K second-fastest, and H slowest, except in monoclinic spacegroups, where K will vary slowest. In spacegroups where negative indices can appear, the sign flips will be considered as an even faster variation. Thus in a monoclinic spacegroup, (1,2,-5) will follow (1,2,5), and (1,2,6) will follow (1,2,-5).

Usage: $WORK/<idname>.asc
Written from: scalem and makemu.
Edited in: Ordinary text editors
Read in: External packages, too numerous to mention.

Report bugs to Andy Howard at howard@iit.edu or 312-567-5881.