Hi,
A new Windows
version of GSAS has been placed on the CCP14 web site. There are some changes
since the Apr. 7, 2005 release. These are:
June 8, 2005
1. Modified GENLES so that the Marquardt matrix modifier is changed before the current cycle. It will
decrease by 20% or less depending on the ratio squared of the minimization function from the current cycle
to that of the previous cycle. Previously, it was modified after the cycle completed. This change improved
LS stability for refinements that required this matrix modifier (extreme damping).
2. Modified the spherical harmonics so that 2500 coefficients are now permitted (old limit was 594). It
doesn't mean of course that one can actually refine that many with a given data set but you can try.
3. Modified RAWPLOT to allow simultaneous refinement of 75 Bragg peaks; I've used it for 56 and this works
just fine.
May 17, 2005
1. Modified FITSPEC so that a multiple scattering and absorption correction is applied to vanadium
data used for neutron TOF incident intensity measurements according to J.M. Carpenter,
Rev. Sci. Inst. 40, 555-556 (1969). FITSPEC will ask for diameter of vanadium rod used in cm &
write the radius on record 'INS VRAD '. If you change rods, edit this record by hand.
2. A new GSAS program has been written, GSAS2MAP, which converts GSAS Fourier maps to other formats.
This facility had been embedded in FORPLOT but is now separate. The maps that can be produced are:
a) ascii file suitable for input to FOX (very big files!), b) DN6 "brix" format readable by a number of
protein graphics programs (includes SPDBV and O), and c) the CCP4 map format which is more widely
readable by protein graphics programs (including SPDBV, O and COOT - real nice!). The CCP4 map file format
wants the space group number (!) not the symbol. Consequently, GSAS2MAP will ask for the space group number
(once) and will keep it for future reference by putting it on the "SG SYM" record in your EXP file. Be
warned that "nonstandard" space group settings may be either unknown to CCP4 or have peculiar space group
numbers (i.e. larger than 230). A list of the allowed ones are in \gsas\data\CCP4_space_groups.txt.
Apr. 13, 2005
1. Eliminated some extra references to parameters not appropriate for nondiffraction histograms
(e.g. scales) that were occasionally created.
2. Fixed some errors in gsas2cif namely long lines for anisotropic thermal parameter records,
missing sig on unit cell volume & underscores in atom type names.
As usual let me know of bugs & requests.
1. Modified GENLES so that the Marquardt matrix modifier is changed before the current cycle. It will
decrease by 20% or less depending on the ratio squared of the minimization function from the current cycle
to that of the previous cycle. Previously, it was modified after the cycle completed. This change improved
LS stability for refinements that required this matrix modifier (extreme damping).
2. Modified the spherical harmonics so that 2500 coefficients are now permitted (old limit was 594). It
doesn't mean of course that one can actually refine that many with a given data set but you can try.
3. Modified RAWPLOT to allow simultaneous refinement of 75 Bragg peaks; I've used it for 56 and this works
just fine.
May 17, 2005
1. Modified FITSPEC so that a multiple scattering and absorption correction is applied to vanadium
data used for neutron TOF incident intensity measurements according to J.M. Carpenter,
Rev. Sci. Inst. 40, 555-556 (1969). FITSPEC will ask for diameter of vanadium rod used in cm &
write the radius on record 'INS VRAD '. If you change rods, edit this record by hand.
2. A new GSAS program has been written, GSAS2MAP, which converts GSAS Fourier maps to other formats.
This facility had been embedded in FORPLOT but is now separate. The maps that can be produced are:
a) ascii file suitable for input to FOX (very big files!), b) DN6 "brix" format readable by a number of
protein graphics programs (includes SPDBV and O), and c) the CCP4 map format which is more widely
readable by protein graphics programs (including SPDBV, O and COOT - real nice!). The CCP4 map file format
wants the space group number (!) not the symbol. Consequently, GSAS2MAP will ask for the space group number
(once) and will keep it for future reference by putting it on the "SG SYM" record in your EXP file. Be
warned that "nonstandard" space group settings may be either unknown to CCP4 or have peculiar space group
numbers (i.e. larger than 230). A list of the allowed ones are in \gsas\data\CCP4_space_groups.txt.
Apr. 13, 2005
1. Eliminated some extra references to parameters not appropriate for nondiffraction histograms
(e.g. scales) that were occasionally created.
2. Fixed some errors in gsas2cif namely long lines for anisotropic thermal parameter records,
missing sig on unit cell volume & underscores in atom type names.
As usual let me know of bugs & requests.
Bob Von
Dreele
