As I just mentioned to Matt, this conversation is NOT moot because a significant fraction of users have bought access. I wonder if it would be possible to make some sort of 'crippleware' version of FEFF(>6) which ONLY runs from within DemLarchTemis? That might make the UW folks a little more comfortable with letting it be available. FEFF9+ will be a harder case because it seems to have been designed to be run by the jfeff interface and consists of separate programs which have to be run in sequence. I suppose a wrapper could be written to orchestrate that. mam On 3/27/2013 5:44 AM, Bruce Ravel wrote:
On Tuesday, March 26, 2013 01:21:58 PM Matthew Marcus wrote:
Just to put my bit in, I believe that the most significant advantage of higher FEFF versions for EXAFS analysis is that it results in more reasonable values for E0 for high-Z elements. I forget whether the issue is high-Z scatterer or absorber. If you use any of the common prescriptions for defining E0 with, say, Pt metal in FEFF6l, your fit will want large values of enot. That said, I have not done a real test by comparing FEFF8 and FEFF6 paths. Has anyone done that?
This is *exactly* my point. Except, as Matt said, for the rather limited, unpublished tests made by him and John many years ago, no one has reported on a substantive test comparing the efficacy of feff6 and feff8 for analysis of EXAFS. (Of course, computation of XANES and other spectroscopies is a different topic entirely.)
Perhaps I would be more interested in fully implementing use of feff8 in my software if someone would offer a better justification than "8 is a bigger number than 6".
FWIW, I agree with Matt that the multi-pole self-energies is a very promising thing that could have a substantial impact on EXAFS analysis. But few of those who claim to want to use feff8 with my software are actually computing and using the multi-pole self-energies.
In any case, I do not have permission to redistribute feff8. So, on a very real level, this conversation is moot.
B
It would be interesting to know what happens if you simulate a k^n*chi(k) with one program and fit it with the other.