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

[Matthew]

OK, I used the default settings.  I'm trying FDMNES now and it seems to do
better with default settings, but it's very slow,
even in 'Green' (multiple-scattering) mode.  That's with a 6A cluster for
comparison.
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.
    mam
----- Original Message ----- 
From: "John J. Rehr" <jjr at leonardo.phys.washington.edu>
To: "XAFS Analysis using Ifeffit" <ifeffit at millenia.cars.aps.anl.gov>
Cc: "John J. Rehr" <jjr at phys.washington.edu>
Sent: Sunday, August 13, 2006 12:22 PM
Subject: Re: [Ifeffit] Attempted XANES calc using FEFF8.1 - what's wrong?


> Hi Marcus,
>
>    In general I would use slightly larger  basis set than you do,
> i.e.. use lmax =2 for O and C, also increase the cluster size.
> If you look at the pDOS, you will see pretty good agreement between
> the *shape* of K-shell expt (xmu.dat cols 2 and 4) which probes l=1.
> The main problems, as I see it, is that the *amplitudes* of the 1st two
> peaks are inverted with FEFF8 (the 1st peak should be higher,2nd peak
> should be lower) and also that there is too much loss.
>
>   Cheers,
>   John
>
>
> On Fri, 11 Aug 2006, Matthew Marcus wrote:
>
> > I tried the XANES calculation on FEFF8.10 with calcite at the Ca K-edge
as
> > the object.  I had just taken some data on this
> > compound, and I wanted to see how it compares.  The attached shows that
it
> > doesn't compare all that well.  I've also attached the
> > feff.inp file I used, which was made by ATOMS using coordinates from the
> > atoms.inp database.  I used default parameters
> > and read the result from the xmu.dat file.  The energy cal on the
> > experimental data was done using the Sb L3-edge assumed at 4132.2eV,
> > since 3um foils of Ca metal are a little hard to handle :-).   Next
stop, I
> > suppose, is FDMNES, which I recently downloaded.
> >   mam
> _______________________________________________
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
>