Scott: I think that Anatoly's posts answer this question. The calculation of the overlaps requires some kind of three-dimensional environment (or the use of the OVERLAP card which I was not familiar with and whose documentation in the FEFF manual is a bit cryptic). There are differences between a single neighbor at a specific distance and a coordination shell of the same neighbor at the same distance. Sam's program clearly does the calculation by building a coordination sphere while Anatoly's method lets FEFF do it automagically. Apparently the results are the same. Carlo On Wed, 5 Jan 2005 scalvin@slc.edu wrote:
Hi all,
A question for Carlo--I guess I'm not clear on what the impact is of tetrahedral vs. octahedral or whatever if all you're doing is a single-scattering nearest-neighbor EXAFS analysis. Isn't a symmetric octahedral arrangment just the single-scattering path with a degeneracy of 6; a tetrahedral a degeneracy of 4; etc.? Why have FEFF calculate anything other than the single-scattering path?
-- Carlo U. Segre -- Professor of Physics Associate Dean for Special Projects, Graduate College Illinois Institute of Technology Voice: 312.567.3498 Fax: 312.567.3494 Carlo.Segre@iit.edu http://www.iit.edu/~segre