Hi Everyone,
New Windows and Linux versions of GSAS have been downloaded to the CCP14
web site. The changes (since 2/2007) are:
June 12, 2007
1. A new record in the .EXP file has been defined:
'HSTnn NFOBS' the number of observed reflections for each phase in a
histogram.
2. REFLIST now can prepare a 'hkl' file suitable for the protein
software CNS.
3. Two new features have been added to the Pawley refinement menu:
The 'P' option produces a Wilson plot of the Pawley extracted
intensities. The plot is made as ln[<F^2>/f^2] vs Q. A well formed
Wilson plot will show deviations at low Q but will form a "reasonably"
straight line of negative slope (= -<Uiso>). In this approximation the
x-ray f is that for a neon atom/10 so the intercept is ln(scale) where
scale is in terms of unit cell contents of electrons for x-ray patterns.
For neutron data the scale is in terms of unit scattering lengths per
unit cell. Significant deviations in this Wilson plot can arise from
misfit background and peak profiles.
The 'W' option permits the inclusion of a restraint to a Pawley
refinement that the extracted intensities conform to a Wilson plot of
specified scale and <Uiso>.
4. The utility program overlp.exe is now included in gsas\exe. It
computes the overlap factors as defined in Von Dreele, J. Appl. Cryst.
40, 133-143 (2007). Input is one or more .REF files from reflist, one
for each histogram. Overlp produces a .TXT file named after the first
.REF file. It is a table of overlap values for each reflection, columns
are: reflection no., 2-theta, 1st histogram overlap factor &
multihistogram overlap factor. Last column shows the effect of using
multiple data sets on the reflection overlap. This .TXT file can be read
into a spreadsheet program for plotting.
5. The PVE file now conains RF**2, Rp and Rwp for each histogram. These
are found at the top of the file before the individual parameter
entries.
6. The Pawley reflection keys have been modified. They are now 'HKL
nnnnnN' instead of 'HKL Nnnnnn'. This facilitates adding more
reflection records.
7. The space group symbol now has all extraneous spaces removed so that
only one will be between axial fields. Tabs are converted to spaces
(done for all typed in input in any case).
Apr. 14, 2007
1. Fix bug in reading 'ALT' style raw powder data. Other types read
correctly.
2. Fix bug in output for .PVE files; the cell angles were missing.
3. Modify SeqGSAS so that it can process data sets in reverse and over
limited sets of data. Some small changes to Seqplot.
As usual, let me know of bugs, errors, "wants", etc.
Since I now have an Intel Mac on my desk, I'll try to make a matching
OSX version (wish me luck!).
Thanks,
Bob Von Dreele
