New version of GSAS

VONDREELE@mist.lansce.lanl.gov
Tue, 15 Nov 1994 12:04:06 -0700 (MST)

GSAS News.......

November 15, 1994
All distribution kits for GSAS have been updated. There were a few bug fixes
and a couple of new features that were in the new manual that hadn't made it
into all the versions. The details:
1. The phase fractions are now given with the correct esds by GENLES for all
histograms. The last version messed these up in some combinations of multiple
phase/multiple histogram refinements.
2. The cell angle output in the setup part of GENLES is fixed. In earlier
versions the gamma angle for hexagonal cells was given as 90.00 deg; internally
the program used the correct angle.
3. Corrections were made the the single crystal routines SCABS, SCMERGE, etc.
This mostly involved corrections to the crystal - orthogonal transformations
and make the absorption corrections more accurate.
4. GENLES now reports a residual based on Fo^2 for powder data anytime the
extraction flag has been set for a histogram. This is similar to "R-Bragg"
but clearly defined to be as close to the single crystal use as possible for
powder data.
5. GENLES now has the facility to refine the Ka2/Ka1 intensity ratio. The
parameter is named KRATIO and is found as a diffractometer constant. Normally
the value is 0.5; if you don't wish to refine it, that is the value GSAS will
assume.
6. A number of changes have been made to the contents of the experiment file
in anticipation of implementing a "SIF" file output routine for GSAS. Some of
these things are changed via new menu items in various places in EXPEDT; none
are essential for normal operation of GSAS.

I have succeeded in producing a PC version of GSAS that runs in MS-DOS via a
"DOS Extender" to enable use of the full machine memory. It is not yet complete
and still needs considerable checking and debugging before it can be released.
However, it appears to perform quite well even on a 33MHz, 486DX laptop,
including graphics! I would like to know what parts of GSAS people would like
to see in such a version. I have implemented EXPEDT, POWPREF, GENLES, POWPLOT,
DISAGL, BIJCALC, GEOMETRY, ORTEP, FOURIER, FORSRH and FORPLOT. Let me know
what else you want.

September 1, 1994
The long awaited new GSAS manual is now done. It consists of 4 Postscript
files which are in the directory [anonymous.manual]. You can either download
the four original files (GSASMANUAL1.PS .. GSASMANUAL4.PS) or take one of the
two backup style files (GSASMANUAL.BAK or GSASMANUAL.TAR) and recreate the
original files on your machine. These files are in the plainest type of
Postscript I can manage but they contain the full manual including drawings.

June 17, 1994
All distribution kits for GSAS have been updated. There have been a number
of bug fixes and minor modifications. Some were done in anticipation of a
new release of the manual. There are also a few new features that have been
added to the system; a short list of details follows.

Changes to GSAS:
1. The "timeout" period for the distribution machine, MIST.LANSCE.LANL.GOV,
has been extended to 10min. This should help with some difficulties people
have had in ftp transfers particularly overseas.
2. FPRIME on VMS systems is working again. There was a mixup between VMS
and UNIX sources in the last release.
3. GENLES now produces a unit cell formula weight and calculated density
based on the actual unit cell contents including atom site fractions. This
output appears after the refined atom parameter listing for each phase. No
esd is given for these values so use them with due consideration of the
errors in the atom fractions and the errors in the "standard" atomic
weights.
4. GENLES now produces a weight fraction associated with each phase
fraction. If a phase was subject to a "leBail" extraction, the weight
fraction will be reported as zero. As with #3, no esd is given.
5. For those of you who use the GSAS library to link to your own codes,
there is in the [anonymous] directory the file "gsas_glossary.lst" which
may help. It contains the argument list for all the routines in GSAS along
with a short (although sometimes nonexistent!) description of what the
routine does.
6. The powder absorption now includes two additional choices for two
versions of a surface roughness correction. One is by Pitschke, Hermann &
Mattern and the other is by Suortti. Both give essentially identical
results and will frequently make a dramatic improvement in the values of
thermal parameters obtained from Bragg- Brentano x-ray data. In some of my
tests the Uiso's from x-ray data came very close the the neutron values
(which of course are correct!) Refinement of them will proceed a little
oddly since both the scales and U's must shift to compensate so GENLES will
give the "diverging refinement" message a few times as these things get to
their new values.

May 2, 1994
There is now a distribution kit available for HP-UX. It is identical to the
other version released earlier. As this is a first release for the HP, there
may be bugs that don't show up in the other versions despite the fact that it
has passed all our QA tests. Those of you that use it please let us know of
any bugs or problems.

Apr. 18, 1994
The newest versions of GSAS for VAX/VMS, Alpha/VMS, SGI Irix and DEC Ultrix
have been placed in their respective directories. This is the first
consolidated distribution so we would like to know of any difficulties you may
have in retrieving the kits and installing them. There is not a kit for HP-UX
at this time.

Changes to GSAS:
1. New hard copy device for "EPS" postscript. This output can be put directly
into PC or MAC word processor documents (Word, etc.)
2. New adjustible X-windows device (graphics option "H").
3. Maximum no. of background terms is 36. This is not tested to its full extent
for any of the background functions. You should expect that some of the
functions may fail in odd ways (overflows, etc.) for very large numbers of
terms; so beware.
4. A rationalization of the GSAS standard for the choice of orthogonal
coordinate system. We had at least three different conventions; now there is
just one.
5. There is a fix to the preferred orientation calculations. It was in error
for non-centrosymmetric space groups. This is now fixed.
6. Remove extraneous output file from ORTEP.
7. Replace all "free format" WRITE, TYPE, etc. statements with formatted ones.
8. Make the colors that appear on various graphics devices more uniform.
9. Fix a bug involving "unobserved" reflections in FOURIER.

We thank all of you that have pointed out the various bugs, errors, etc. Many
of the above fixes resulted from your input. Please keep 'em coming!