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 ,_. | \ | v- ,' \ | ( \__Montevideo, Uruguay 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 _____ Heriot-Watt University is a Scottish charity registered under charity number SC000278. No virus found in this incoming message. Checked by AVG. Version: 8.0.101 / Virus Database: 270.4.3/1526 - Release Date: 6/30/2008 8:43 AM
