Hi Santu
Start from a dummy
atom ( a Hydrogen atom in arbitrary position) refinement (Le Bail mode) to
obtain converged parameters (zero point, cell, background, and profile R3 or
R4) first. Lock the parameters and replace the Hydrogen with your target
atoms coordinates and start refine again(Rietveld mode). unlock your parameters
a few at a time. Go to CCP14 for examples of how to proceed.
Xiang
Ouyang, Ph.D.
Manager of the
Single Crystal X-ray Facility
Department of
Chemistry
University of
Ottawa
10 Marie-Curie
St.
Ottawa, Ontario K1N
6N5
Tel: (613)5625800
ext. 6664
-----Original Message-----
From: santu chakraborty [mailto:[EMAIL PROTECTED]
Sent: Friday, July 09, 2004 1:25 AM
To: [EMAIL PROTECTED]
Subject: Problem: GSAS
Dear all,We are trying to solve a powder crystal structure containing Praseodymium ( At. No. 59) as heavy atom. We have index the powder pattern by using the programme TREOR and DICVOL . Both gives the same results with a very figure of merits ( 23, 45). We have got the Pr co-ordinate by using the programme TOPAS and it supports the profile fitting in TOPAS. But the problem is when we are trying to refine this structure using this Pr coordinate with the help of programme GSAS, it's unable to refine and the refinement diverges.Can any one tell me how can we proceed from here with GSAS or what is wrong with us ?Thanking you in advance.Santu ChakrabortyDept.of PhysicsJadavpur UniversityKolkata-700032IndiaYahoo! India Careers: Over 50,000 jobs online.
