[Ifeffit] What does FEFF stand for?

Scott Calvin dr.scott.calvin at gmail.com
Tue May 10 14:03:23 CDT 2011

Right, Chris.

There is a factor in the EXAFS equation, f(k). In different parts of  
the literature, f(k) sometimes has different meanings, but within the  
context of FEFF it refers to the effect of the potential of the  
scattering atom on both the scattering amplitude (the real part) and  
phase (the imaginary part).

Thus, it stands for "f effective."

My understanding, although I could be wrong is that the "effective"  
part came from an improvement of the theory to account for curved-wave  
effects. In other words, early theories approximated the photoelectron  
as a plane wave, but of course it spreads out radially from the  
absorbing atom. That change necessitated tweaking the definitions of  
the factors, so it became the "effective" f.

--Scott Calvin
Sarah Lawrence College

On May 10, 2011, at 11:53 AM, Christopher Patridge wrote:

> On 5/10/2011 2:49 PM, Francisco Garcia wrote:
> Dear all,
> I wish to ask a somewhat novice question: What does the acronym FEFF  
> stand for?
> Thank you.
> _______________________________________________
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov<mailto:Ifeffit at millenia.cars.aps.anl.gov 
> >
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
> I am pretty sure it stand for the calculated Effective Scattering  
> factor  F(eff)ective.
> buena salud,
> Chris Patridge
> <ATT00001..txt>

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