Hi All,
I have placed on the ccp14 ftp server new versions of GSAS for Windows,
RedHat Enterprise 4, Fedora 5 and Mac OSX 4. The changes are:
1. The maximum number of profile points in an individual powder pattern
is now 200,000.
2. The program OVERLP has been extensively modified. The computation of
the overlap factor has been changed to be more "rational" (the earlier
version may have been in error). An additional file, name.HKL, is now
output which has the <F^2> values, their sigmas, derived Fobs values
from averaging the individual F^2 values and phases . The FWHM is
modified by the overlap factors to give an "effective" FWHM taking into
account of the extra information gained from the reflection
displacements between multiple histograms. It also tabulates an
effective "completeness" table by data collection "shell".
3. The restraints have been extensively modified to handle 2-site
disorder in protein structures. Alternate atom sites must be indicated
as "A" and "B" in the PDB name (the 4th character in the name). The
alternate atoms must be collected together by residue in the atom list,
"A"s before "B"s as is usually generated by e.g. Coot. Three or more
site disorder is not addressed.
4. The coupled torsion angle restraint ("Ramachandran restraint") has
been further modified. It now follows a pattern similar to that used for
torsion restraints. Tables of pseudopotential terms are inserted, each
with a unique name (e.g. "ALA-1") into a single histogram. The
restraints are then inserted each with one of these names to indicate
which pseudopotential surface is to be used for that restraint. This way
all coupled restraints can be contained within a single histogram rather
than having ~30 individual histograms one for each type. There is now
just a single Macro file, "2-torsion.mac", that is needed to generate
these restraints. Users with old protein structure EXP files who want to
continue using them will need to use a "hand editor" (e.g. PFE) to
remove the old histograms and modify the HTYPE & NHST records. Then in
EXPEDT insert the new "R" restraint type histogram using 2-torsion.mac.
5. The CNS output file from reflist has been changed. Apparently CNS
wants Fobs & phase (0-360 deg) not Fa & Fb.
As usual, let me know of errors, bugs, "features" and other things as
you try this out.
Thanks,
Bob Von Dreele
