[Ifeffit] Attempted XANES calc using FEFF8.1 - what's wrong?

[John J. Rehr]

Hi Matthew,

> I think there are more serious disagreements than just the amplitudes of two
> peaks:
> 1.    The pre-edge features are missing in FEFF (and FDMNES).
> 2.    The big second feature that's split in experimental data isn't in
> simulation.

   Actually some pre-edge features and the split in the 2nd feature are
visible in the pDOS. To see the preedge in FEFF one has to shift the
Fermi energy by 2 eV (Vr=2) to get the Fermi energy right. Also, 
one has to cut the loss, Vi = -.3 eV.  Matt's remarks illustrate one of
the problems with the defaults in FEFF8, namely that the plasmon-pole
self-energy has too much loss in the near edge. It might be worthwhile
to compare results with another exchange model, e.g. Dirac-Hara exchange.
or ground state.

  John