Re: [Ifeffit] FEFF report: Hard tests failed in fovrg.

Hi all, I think that several of the points raised in the last few replies will be better addressed off-ML. (See above) As for the benefits of FEFF9: * calculation of potentials is more stable and more accurate * improved self-energy (-> better peak positions and widths) * ability to use high-quality ab initio Debye-Waller factors (this will currently be beyond the skill of many users, but will be semi-automated in an upcoming release of FEFF9) * alternative "RPA" core hole * ... and don't forget: * 15 years of ironing out problems Cheers, Kevin Jorissen On Wed, Aug 7, 2013 at 12:47 PM, Bruce Ravel wrote:

Hi Matthew,

On 08/07/2013 03:35 PM, Matthew Marcus wrote:

...

2. The later FEFFs use a different structure, in which the modules are separate programs. Can this be integrated into Artemis?

I don't see that as a problem. Demeter already does a lot of crazy things, including playing around with the CONTROL values and replacing Feff's pathfinder with one that I wrote.

Going back to point 1, any "FEFF9L" would need to be a

...

wrapper which executes the modules in correct sequence.

I doubt that Feff9L would be a drop-in replacement in Artemis, but if Feff9L were a defined thing, then I (and other software authors -- yourself, for example) would have a defined target to work against.

5. Is there some documentation showimg how FEFF(>6) is better than

...

FEFF6L for EXAFS alone? Under what conditions should we be dissatisfied with FEFF6L?

Umm ... well ... perhaps when fovrg fails its hard test? :)

I know that FEFF9 has all kinds of nice things that it does, but

...

many of these are irrelevant for Artemis use.

This is a recurring topic on this list and a most excellent question. As I have written before, there is some anecdotal evidence that self consistent muffin tins are an improvement in terms of the values of E0 needed for a good fit. But I am not aware of a rigorous investigation that has been published in any form (journal article on down to wiki page).

I think that simply having a version of FeffN (with N>6) in a form that I can properly target in Demeter would be a real boon in that it would be a lot easier to automate such tests.

B

-- Bruce Ravel ------------------------------**------ bravel@bnl.gov

National Institute of Standards and Technology Synchrotron Science Group at NSLS --- Beamlines U7A, X24A, X23A2 Building 535A Upton NY, 11973

Homepage: http://xafs.org/BruceRavel Software: https://github.com/bruceravel ______________________________**_________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.**gov http://millenia.cars.aps.anl.**gov/mailman/listinfo/ifeffithttp://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit