[Ifeffit] XANES relative peak energies

[jjr at u.washington.edu]

Hi Ross et al.

  The answer depends to some extent on which peaks you are talking about.
Getting peak positions right requires good scattering potentials (large
enuf clusters and l_fms and sometimes fiddling with muffin-tin radii),
converged full multiple-scattering calculations (large enuf clusters, 
large enuf lmax). It may be difficult to get the edge peaks right with the
spherical muffin-tin potentials in FEFF. An additional effect is the self-energy,
but the Hedin-Lundqvist model often does a good job. You might try using
Dirac-Hara for molecular solids.

  J. Rehr

On Mon, 23 Sep 2013, Ross Devol wrote:

> Hi everyone,
>  
> I am using FEFF to calculate XANES spectra for calcium carbonates, and I am wondering how precisely I should expect the relative peak energies should be
> consistent with experiments. Is there anything I can do within FEFF to shift peaks relative to each other or to stretch/compress the entire spectrum?
> I've tried increasing l_fms (or lmax2), which helps some but not enough.
>  
> Thank you!
> 
> Ross DeVol
> University of Wisconsin-Madison
> 
>