[Ifeffit] FEFF83 question

Bruce Ravel bravel at bnl.gov
Thu Jul 5 10:53:58 CDT 2012

On Thursday, July 05, 2012 03:33:12 PM Pal, Rhitankar wrote:
> I am using FEFF83 and IFEFFIT recently to calculate the EXAFS spectra of
> Mn-cluster in PhotosystemII.
> I would like to know what is the E0 value FEFF83 uses for a Mn atom. Does it
> use the same E0 for all the absorbing atoms if there are multiple Mn atoms
> in a cluster.

The interstitial energy is reported in Feff's output files as "vint".
This does not necessarily have any relationship with the e0 parameter
in Ifeffit's background removal algorithm.  That fact is the reason
that a variable e0 parameter is almost always needed in a fit to EXAFS

There is only one absorber in a cluster in a Feff calculation, so
there is only one atom for which an interstitial energy is calculated.
Nothing guarantees that Vint will be the same if you switch which atom
in the custer is the absorber.



 Bruce Ravel  ------------------------------------ bravel at bnl.gov

 National Institute of Standards and Technology
 Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2
 Building 535A
 Upton NY, 11973

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