EXAFS FEFF code

A back Fourier transform on individual peak can be then applied to isolate individual contributions. The so-obtained filtered EXAFS signal is analyzed in order to determine the related structural parameters N, R and a. A common method consists to build a theoretical model from the relation (2) using known electronic parameters for X(k), So2, Aj(ir,k) and Oy (k), and, by treating N, R, and a as free parameters, to minimize the difference between the theoretical and experimental curves. The electronic parameters can be evaluated from EXAFS signals recorded for references of known structures or from theoretical calculations using the efficient ab initio FeFF codes [7, 8],... 

Because the R term, and the mean-free path of backscattered photoelectrons is small (usually < 25 A), typically the total number of shells rarely exceeds 7. The backscattering amplitude, Fj(k), and phase shift, dj(k), for the absorber-neighbor pair may either be extracted from the EXAFS of reference materials or calculated theoretically using widely available codes such as the FEFF developed by John Rehr s group at the University of Washington. ... 

---