[Ifeffit] XANES relative peak energies

jjr at u.washington.edu jjr at u.washington.edu
Mon Sep 23 11:34:24 CDT 2013

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

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