Hi All, There is a new version of Windows GSAS on the CCP14 web server. The biggest change is that it will now do Pawley style extractions for one set of reflections from multiple powder patterns. This is done inside GENLES. See below for note on this & other changes. Linux & other versions will follow soon. As usual please let me know of bugs, etc. Bob Von Dreele GSAS News....... June 3, 2004 1. Fixed errors in arcsin, arccos & arctan2 routines that gave misbehavior in texture and possibly other calculations when the result angle was 0, +/-90 or 180. 2. Fixed a mishandling of the last profile point under some circumstances. 3. Made defaults for sample angles for sph. harmonics as follows: constant wavelength x-ray: omega=0, chi=0, phi=0; omega follows 1/2*2-theta for Bragg-Brentano neutron (TOF or CW) : omega=0, chi=90, phi=0; omega fixed for Debye-Scherrer These can be overridden, for example, in the iparm file by entering records similar to: INS 1CHI 90.0000 INS 1OMEGA 0.0000 INS 1PHI 0.0000 for Debye-Scherrer geometry for x-ray powder diffraction (common for synchrotrons). 4. A new polarization function has been added (#4). This is to be used for image plate data where the "intensity is not conserved" (in Fit2D parlance). Thus, the calculated pattern requires an additional scaling by sin(2-theta) to correct for the increase with 2-theta owing to the longer integration arc. The names of Lp corrections #0 and #1 have been changed to reflect their true nature. May 17, 2004 1. A new capability has been installed in GSAS. It will do a multipattern Pawley refinement against a single list of reflections. The reflections can be from more than one phase and the patterns can be subject to refinements where some phases are done by Rietveld and others by Pawley (not tested). The Pawley set of reflections can also be subject to a restraint against negative values. For conventional CuKa data a single reflection entry is used to represent both Ka1 and Ka2 peaks; the RATIO parameter is used to scale them appropriately. The results are in the EXP file so they can easily be used for other purposes. Be aware that POWPREF will wipe out results from previous Pawley refinements and that much the same care in beginning refinements after POWPREF when doing LeBail refinements also must be done with Pawley refinements. May 7, 2004 1. The Finger, Cox & Jephcoat peak shape functions have been improved in precision & speed (Thanks to Larry Finger). They now do a better job on very low angle peaks and are ~50% faster. 2. A bug in the constraint editing for profile functions has been fixed. It used to prevent one from entering a constraint for profile parameter #21 or larger.
