[Ifeffit] feff82 issue with perovskites
John J. Rehr
jjr at phys.washington.edu
Mon Mar 3 10:53:57 CST 2008
Thanks for the comment.
As you've seen Ba has a sharp edge resonance which confuses the defaults
for calculating phase shifts in FEFF. To tame it, add a little broadening
and a finer grid:
EXCHANGE 0 0 1.0
and the problem seems to goes away. Also, the problem does not appear
to be visible with FEFF8.4. Fortunately (I think) this is an unusual case.
On Mon, 3 Mar 2008, Francesco Giannici wrote:
> Hi all,
> when calculating paths around Ba (K-edge) in the cubic perovskite BaZrO3, the third path (Ba-Ba) is totally screwed up in the 2.6 - 3.8 ang^-1 range, with amplitude going up to 1000. You can find the input file at http://giannici.altervista.org/feff.inp
> Actually, this is also the case of Gd:BaCeO3, substituting one Gd for one Ce, and calculating paths for the Gd K-edge: the Gd-Ba path shows the same issue. This applies to Feff8.2 on Debian, Fedora, and MacOSX 10.4.11. I found that playing around with FOLPs seems to help, but I´m not very confident with that, and I´d like to hear your opinion on what the cause could be. (Yeah, just throwing away all those low-k data would also be a solution).
> On the other hand, Zr and In K-edge in Ba(In,Zr)O3 work just fine, as do Ce, Ba, Y and In K-edges in Ba(Y/In,Ce)O3. Also Gd K-edge in Gd2O3 works fine.
> Cheers from Stuttgart,
> Francesco Giannici
> Dip. di Chimica Inorganica e Analitica
> Università di Palermo / ISMN-CNR
> giannici at pa.ismn.cnr.it
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov
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