Anatoly, I don't quote your answer because I would like to add some more elements to specify what I'm searching for. In my previous post I have used the term "cluster" in a wrong way, that is I was thinking at the crystal-box (normally less than 216 atoms) used in the ab-initio density functional theory calculations and "doped" with few percent (< 10%) of an absorbing atoms. For example, if we put 5 absorbing atoms in a box of 64 (that represent the crystal host) we have 5 possible configurations for our FEFF calculation and is impossible in an EXAFS fit to include all the important paths (too many!). My idea to take into account the numerical simulation and combine it with the experimental EXAFS data could be to use the pair radial distribution function extracted from the simulation, average the configurations, recalculate paths and proceed in the fit. Well, I hope now is more clear... In any case, thank you for the useful article! Mauro Frenkel, Anatoly wrote:
Mauro,
If I do understand your question correctly, you may be asking how to handle a multiple of inequivalent sites in atomic clusters with N atoms, where each atom generates a unique sequence of single- and multiple-scattering paths. A possible solution is given in this article:
D. Glasner and A. I. Frenkel Geometrical characteristics of regular polyhedra: Application to EXAFS studies of nanoclusters AIP Conf. Proc. 882 , 746-748 (2007). https://exchange2000.bnl.gov/exchange/frenkel/Drafts/RE:%20%5BIfeffit%5D%20%...
The PDF is here:
http://pubweb.bnl.gov/users/frenkel/www/XAFS13-Proc/clusters-geometry.pdf
It is the same type of averaging and radial distribution analysis approach that you are proposing unless I misunderstood your question.
Anatoly
--
Mauro Rovezzi