On Wednesday, March 13, 2013 08:24:41 PM davood dar wrote:

1. * 1*. What is the ideal value of R- factor for any fit.

R-factor is a way of expressing percentage misfit. Smaller is generally better, although smaller is not better if other aspects of the fit are not defensible. For instance, if one of the fitting parameters is physically unreasonable, then getting a smaller R-factor is not so useful. R-factor is just one of the ways that the quality of the fit is evaluated. I discuss in some detail the statistical parameters reported by the software here: https://speakerdeck.com/bruceravel/advanced-topics-in-exafs-analysis

2. * 2. * Can we use (fit) the theoretical model generated from square pyramidal structure to EXAFS data of octahedral structure by assigning degeneracy of 2 for the apical atom. OR using octalhedral for square planar by not using apical path

Making clever use of Feff calculation on known structures to investigate unknown structures is something I talk about in https://speakerdeck.com/bruceravel/modeling-non-crystalline-samples Lots more information at http://xafs.org and at http://bruceravel.github.com/demeter/ B -- Bruce Ravel ------------------------------------ bravel@bnl.gov National Institute of Standards and Technology Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2 Building 535A Upton NY, 11973 Homepage: http://xafs.org/BruceRavel Software: https://github.com/bruceravel