RE: new gsas
Dear Dr. Von Dreele, What is the unit of scattering length density in GSAS from the Fourier output, for different types of Fourier maps respectively? Sometimes huge values are obtained for Patterson plot. Is there a way to normalized the values, for example, to number of electrons/A^3? Many thanks. Sincerely, Ling Yang -Original Message- From: Von Dreele, Robert B. [mailto:[EMAIL PROTECTED] Sent: Thursday, May 03, 2007 5:26 PM To: rietveld_l@ill.fr Subject: new gsas Hi All, New versions of GSAS for Windows and Fedora-5 have been placed on the CCP14 web server. The changes are as follows: May 2, 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. 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, features, etc. you may find. The RedHat Enterprise MacOSX versions will be made later. Best, Bob Von Dreele
Is it possible in GSAS to control the value of certain parameters in a
For example, Uiso0, 0F1, etc Thanks a lot. Sincerely, Ling Yang Current address: Bldg 8600, MS 6460 SNS, Oak Ridge National Laboratory Oak Ridge, TN 37830 Tel: 865 574 0350 Fax: 865 241 5991
May I ask where to buy some plastic balls and rods
to build a lattice? It will be better if they are colorful and flexible to change the bondangle. Thanks. Sincerely, Ling YangDept of CME, Univ of CincinnatiCurrent address:Bldg 8600, MS 6474SNS, Oak Ridge National LaboratoryOak Ridge, TN 37830Tel: 865 574 0350Fax: 865 241 5177
A question about stacking faults
Dear all, Are there anybody experienced in stacking faults? Please help me! Basically I'm following Warren's book and R. Berliner's paper to simulate the possible effects of stacking faults on diffraction patterns. I did generate a set of patterns for fcc, butthere are some questions I'm not clear: 1 What is the relation of(hkl) between the cubic fcc and the hexagonal lattice cell, for example, what does this (1 0 1/3) stand for in the orginal cubic cell?All those papers usethe distance between layers as the c value, i.e., A=-a/2+b/2, B=-b/2+c/2, C=(a+b+c)/3, the original (111) plane will be (-1 1 3). I don't know what is this l=1/3 or 2/3 stand for. 2 Besides peak broadening and peak position shifting, are there other effects by the long-range one-dimensinal disorderness?Is it possible to get superlattice peaks which have bigger d-space than the original cell? Should I set a superlattice layer sequence first, e.g., the fcc sequence is ABCABC..., should i set a sequence like ABCDEFABCDEF... as a model for simulation, so that extra peaks will appear? Please please help. Thanks greatly. Sincerely, Ling YangDept of CME, Univ of CincinnatiCurrent address:Bldg 8600, MS 6474SNS, Oak Ridge National LaboratoryOak Ridge, TN 37830Tel: 865 574 0350Fax: 865 241 5177
Has anybody answered Yong-Il Kim 's question about occupancy
I have the same question, so post his question here: Dears all, In the structural refinement of ABO3 type, e.g. A1-xCxB1-yCyO3 using GSAS. The dopant (atom C) may be occupied two atomic sites, A and B. Therefore the occupancy constraint should be considered. In order to perform the structural refinement of A1-xCxB1-yCyO3 allowing the occupancies of atom C in the A and B sites to be varied but the total occupancy of atom C must be fixed. How can I define the linear constrain in GSAS? The constraints set as follows, and then how to define the other constraint (g4+g5=fixed)? Would you give me any advice? # Atom x y z g #1 A x1 y1 z1 g1 #2 B x2 y2 z2 g2 #3 O x3 y3 z3 g3 #4 C x1 y1 z1 g4 #5 C x2 y2 z2 g5 #Phase variable atom no. coeff 1 frac11 1 frac4 -1 1 frac21 1 frac5 -1 Thanks in advance, Charles
[no subject]
Dear all, I have some questions concerning the refinement of the gppd data and would appreciate your advice: 1) The patterns show some kind of texture(up and down on the error curve), but the sample is powder(although maybe the granules are large) and should be isotropic. All banks show this characteristic texture behavior. 2) For different banks, the sign of error for the same (hkl) gradually reverse, and it's hard to refine. 3) If UISO factors are let free, the refinement will go bad, even if they are constrained. 4) For one series of sample, the peaks are really sharp, the error sign is always like -/+/-, the positive error is very big and sharp. 5) There are some small peaks, which may be due to martensitic transformation. But they are really small, i don't know to what degree i should trust these data. Somebody said maybe that's due to contamination. If it is martensitic trans., how can i set a proper model to refine the data? Sincerely, Ling YangPhD student in Dr. Wang's group701 Scarboro RdOak Ridge, TN 37830Tel: 865 574 0337Fax: 865 241 5177
Rawplot refinement formula
Hi, May I ask what is the exact formulaused byrawplot refinement? There are 6 parameters: pos, int, alp, bet, sig, gam, what are their meanings? If i want to compare the changes of a peak at different banks or different temperature, what is the most important parameter? Thanks:) Ling YangPhD student in Dr. Wang's group701 Scarboro RdOak Ridge, TN 37830Tel: 865 574 0337Fax: 865 241 5177
