Dear Bruce In your "Introduction to FEFFIT" (http://feff.phys.washington.edu/~ravel/) you suggest in the beginning to use the DW factor according to the Debye model [debye(temp, thetad)] for the simple Cu foil. Then you ask to try with the Einstein model. I gave a look at the theory but I did not understand how to apply it to the fit. Anyway performing some FEFF calculation of this Cu foil, it looks that the Debye model works quite well but I am a very beginner feffusers and I am not an expert about IFFEFIT too. Anyway the samples I have to analyze are metallic alloy mainly based on Fe with some diluted element such as (Cu, Ni, Mn each less than 1at%). Is the Debye model good approximation for transition metal alloy? Is it better just to leave all Debye Waller factors free? In FEFF calculation, does it have any meaning to use the NOHOLE card and the S02=0.9? Thank you for your help Best regards, Sebastiano Cammelli