[Ifeffit] Re: [Feffusers] Fwd: Some question about FMS calculation with FEFF

[Bruce Ravel]

On Thursday 09 February 2006 01:57, Michel Jaouen wrote:
> Now a question about Hephaestus: for f' and f" one has rodio buttons
> allowing to select among various set (Crmer Liberman, Henke, ..). I
> have try to select several and it always return CL! Why and how to
> fix this (not sure it is a bug but?).

To quote from the Hephaestus document about the f'/f" utility:

   This utility plots the complex corrections to the scattering
   factors for the elements. i.e. the energy dependent f'(E) and f"(E)
   terms. These functions are tabulated from the Cromer-Liberman
   calculations for the isolated, neutral atom.

The selection in the Resource menu is ignored.  That's by design.  The
reason is that I have never been able to figure out how to do the
interpolation off of Chantler's ffast tables near the absorption edges
such that the f' function is well behaved near the absorption edge.
The dteails are at
http://physics.nist.gov/PhysRefData/FFast/Text/cover.html.  The last
time I looked at this in detail, my implementation gave very poor
results in the region of f' that was changing quickly.

B


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 Bruce Ravel  ---------------------------------------------- bravel at anl.gov

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