RE: Problem: GSAS

[Kaduk, Jim A]

Title: Message

What is the unit cell?  Have you tried looking for analogous compounds with the same (or similar) unit cells?  You might be able to avoid solving the structure if a model is already out there.  What is the space group?  It may be that it is one with a floating origin, and that you may need to fix one or more of the Pr coordinates to keep the refinement stable.

 

Jim  Kaduk

BP Chemicals

Naperville IL USA

-----Original Message-----
From: santu chakraborty [mailto:[EMAIL PROTECTED]
Sent: Friday, July 09, 2004 12:25 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 Chakraborty

Dept.of Physics

Jadavpur University

Kolkata-700032

India

 

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