Dear Gerard,

You should define a new kind of atom, add the corresponding scattering
factors identical to the real one and use the normal atom on one site and
the new atom in the other site. I think GSAS manual explains how to define a
new kind of atom but if this were not the case you can also use an already
know atom and change scattering factor parameters to make it equal to the
real atom (you can do it directly in the .exp file with cut/paste in a text
editor) and then refine f’ and f’’ for both different atoms/sites.

I hope this helps.

Leo

 

Dr. Leopoldo Suescun                                    

Prof. Adj. de Física                                  Tel: (+598 2) 9290705

Cryssmat-Lab./DETEMA                                  Fax: (+598 2) 9241906

Facultad de Quimica, Universidad de la Republica

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From: Gerard, Garcia S [mailto:[EMAIL PROTECTED] 
Sent: Tuesday, July 01, 2008 11:29 AM
To: rietveld_l@ill.fr
Subject: anomalous scattering factors 

 

Dear All,

I have a small question regarding GSAS and there is no better place to ask
than in this great forum.

I  would like to refine anomalous scattering factors (the f' and f'' found
following the keyboard route LOF, for DOS users)
of two identical atoms occupying different crystallographic sites.

Following the above-mentioned route I just find the possibility of refining
the anomalous scattering factors of each type of atom.
I have two identical atoms in different crystallograhic sites  but i can
only refine one set of f' and f'' values.

I have seen it done in some papers using GSAS (i.e. J. Phys. Chem. Solids
Vol. 52, 1257 (1991)), but I just do not find the right path or option.

Regards



Gerard 

 

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