Hi Falk, These pages may help:
http://cars.uchicago.edu/ifeffit/FAQ/FeffitModeling?highlight=%28doping%29#How_do_I_handle_doped_materials.3F_Why_doesn.27t_Atoms_handle_doped_materials.3F http://cars.uchicago.edu/ifeffit/Doped http://cars9.uchicago.edu/~ravel/software/doc/Atoms/Atoms/node4.html#SECTION00440000000000000000 --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 _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit