Dear Maria,
I agree with Dr. Retief, I would never refine structure details like atomic
coordinates or temperature factor (displacement factors) for QPA!
Regards
Francois Girod
"Retief, Johannes
\(JJ\)" Pour
:<[email protected]>
<[EMAIL PROTECTED] cc :
l.com> Objet:RE: Question
on temperature factors
01.07.2005 08:50 ZE2
Veuillez répondre Ã
rietveld_l
Hallo Maria,
Temperature factors are strongly correlated with surface roughness.
Refining them using X-rays easily lead to rediculously large positive
values or even negative values. My advice would be to fix them at the
theoretical values, especially for the QPA of a complicated system.
Regards,
Johannes Retief
-----Original Message-----
From: Maria Chrysochoou [mailto:[EMAIL PROTECTED]
Sent: 30 June 2005 21:55
To: [email protected]
Subject: Question on temperature factors
Hi all,
I have a question on temperature factors in Rietveld refinement.
I am on working on a complicated system with over 12 phases on
average (it is cement-like in chemistry and mineralogy). I tend not
to refine temperature factors in order to reduce the number of
refinable parameters to a realistic number.
Do you think that the temperature factors make a big difference in
quantitative analysis? Could you give me a range of reasonable values
for an ambient temperature cement?
Thank you,
Maria Chrysochoou
W.M. Keck Geoenvironmental Laboratory
Stevens Institute of Technology
Tel.: +1 201 216 8773
Fax: +1 201 216 8212
E-mail: [EMAIL PROTECTED]
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