[Ifeffit] Ifeffit Digest, Vol 52, Issue 7

[hebhop at u.washington.edu]

Hi Eckhard,
you need to add the following two cards to your feff.inp files:

* Self consistent potentials. This can be important for XANES calculatoins.
SCF rscf 0

* Full multiple scattering (sums all paths within rfms). This is essential for 
* most XANES calculations.
FMS rfms 0

calculations should be converged w.r.t. rscf and rfms, but for your files, you can just include the whole cluster of atoms. 
Also, I ran both files and the first one (gypsum) complains that atoms are very close together. FEFF does not crash, but I would check your structure to be sure that it is correct.
Cheers,
Josh Kas

> Hallo @all,
>
> (first at all, sorry for my bad english)
>
> i'm a student working on my diploma thesis (nexafs/xanes) and my job is to
> simulate with FEFF 8.4 spectra, for example absorption as a function of
> energy (mu_(E)). I'm a newbie in this topic and i tried to get the k-edge
> of Sulfur for the substance gypsum (CaSO4 * 2(H2O)) and pyrite (FeS2). I'm
> interested in the XANES-range of the spectra not the EXAFS. I get
> everytime my peaks at ~2472 eV for Sulfur as absorber whatever substance i
> use (gypsum, pyrite,...). There are no differences with the peak position
> on the energy-scale or shifts. I'm really confused :-( I think, there
> should be differences in the spectra... I send you two feff.inp files from
> my feff-runs. My source is the mineralogy database
> (http://rruff.geo.arizona.edu/AMS/amcsd.php) where i get the data for the
> unitcell. Then i put the data in the XtalDraw program to get the positions
> of the Atoms in Angstrom, by the way i get i nice 3D-View of the unitcell
> :-). Then i put the values of the positions into feff...
> I simulated pyrite with 12 atoms and gypsum with 48.
> I'm appreciative for every help :-)
>
> ciao,
> Eckhard
>
>
> ---------------------------------
> Eckhard Bosman
> e.bosman at stud.uni-goettingen.de
> +49 (0)551-39-14441
> Raum: E0.104
> Institut f?r R?ntgenphysik
> Friedrich-Hund-Platz 1
> 37077 G?ttingen
> Germany