Hi Falk, These pages may help: http://cars.uchicago.edu/ifeffit/FAQ/FeffitModeling?highlight=%28doping%29#H... http://cars.uchicago.edu/ifeffit/Doped http://cars9.uchicago.edu/~ravel/software/doc/Atoms/Atoms/node4.html#SECTION... --Scott Calvin Sarah Lawrence College On Aug 7, 2012, at 10:52 AM, Meutzner, Falk wrote:
Dear Matt, dear community
thank you for your fast reply! I am not sure, if I understand you correctly. I tried what you suggested, but the result is just the same. I will try to give some more insight:
Our binary system is bcc (pm-3m), there is one atom on the position (0,0,0) and another one on the position of (0.5,0.5,0.5). After creation of the material, we have a chemically disordered state. Any of the two atoms can occupy any of the aforementioned positions. After heat treatment however, the material chemically orders itself and becomes CsCl structure. In theory, atom A will always be on the corner at (0,0,0), while atom B will always be in the centre of the cell at (0.5,0.5,0.5).
Our problem is, we would like to distinguish between these two phases, because we possibly have mixtures of the ordered and disordered states.
We already achieved the ordered state with atoms, because they are unique positions (Atom A at (0,0,0), atom B at (0.5,0.5,0.5). Unfortunately we are unsure how to model the disordered state. We would need the possibility to tell the programme, that the observed atom will always be A at (0,0,0), while the other atom has a possibility of 50% to be A and 50% to be B.
For the programme it seems not to matter which of the positions our observed atom is at. Therefore the calculated spectra are the same.
I hope I was able to give more insight into our problem. Thank you! Best Regards Falk