Fuxiang,On Thu, Jun 23, 2016 at 4:47 PM, Fuxiang Zhang <zhangfx@umich.edu> wrote:Hi, Scott,In fact, I have a series of single crystal Ni-Fe alloys (Fm-3m) with known atomic ratio, and measured both Fe and Ni edges for samples and standards. I just want to see if there's any difference between the local bonding environment of Fe and Ni, such as R, N and sigma2. Now using the suggested method by Matt by changing atoms in FEFF.inp file, I can only get ss, deltr and E0 from fitting (I don't know how to refine N and R).You can refine N and deltaR for any scattering path. R is Reff + deltaR, so that *is* refining R. When you say "I don't know how to refine N and R", I'm left unsure what part you do and do not know. There are lots of on-line examples and documentation. If you're having trouble, it might help to ask a specific question.But the fitting with Ni (or Fe) edge can only generate the same R and deltr for Ni-Ni and Ni-Fe pairs.I'm sorry, I don't understand. In principle, the Ni-Ni distance and Ni-Fe distances can be different, of course.Fitting the edges of Ni and Fe will yield a little difference in the R and deltr. Which results should I believe, or something wrong I am using the program because I cannot generate different R for Ni-Ni and Ni-Fe pairs with the same data set.Many thanks for your suggestions and helps.I can't tell whether you're saying you do not know how to tell Artemis to refine different distances for Ni-Ni and Ni-Fe, or that when you do tell it to do this that the result is that the two distances are the same.As said earlier, unless you're looking at some weird situation, I would expect measuring distances and coordination numbers separately for Ni-Ni, Ni-Fe, Fe-Fe, and Fe-Ni to be very, very hard. My recollection (could be wrong) is that the nominal near-neighbor distances for fcc Ni and bcc Fe are both around 2.48 Ang. With Z different by only 2, I would not expect these to be distinguishable.But the program definitely allow you to try....--Matt Newville
_______________________________________________
Ifeffit mailing list
Ifeffit@millenia.cars.aps.anl.gov
http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit