[Ifeffit] [howto] configurational average in EXAFS with FEFF

Mauro Rovezzi rovezzi at esrf.fr
Tue Mar 27 08:38:00 CDT 2007

Dear all,

I would like your point of view on how to approach configurational
average in EXAFS analysis with FEFF (let's not consider GNXAS for the

In particular, I'm trying to combine ab-initio DFT numerical simulations
with EXAFS for doped semiconductors where in the minimized cluster there
are N absorbing atoms.

Usually I don't use the CFAVERAGE card because fractional degeneracies
are not taken into account and, to have a qualitative analysis, I
calculate an "extended"-XANES (up to 8.0 A^-1) for each cluster - where
each absorbing atom is shifted to (0,0,0) - and then I average over all
single-cluster signals.

Well, at this point my question is: how to proceed in the quantitative
analysis with Ifeffit? In fact, considering only single-scattering
expansion for all the clusters the result could be seen as a radial
distribution for each scattering pair where the integral gives the
coordination number and the FWHM a structural Debye-Waller factor. How
to combine these informations?

Thanks for the answers,

Mauro Rovezzi <rovezzi at esrf.fr>
PhD student - GILDA BM08 c/o ESRF (Grenoble, FR)

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