Scott, Michel, Scott Calvin wrote:
FEFF8 does give at least one improvement for EXAFS, which I've used on occasion: the self-consistent field calculation can be used to give an improved estimate of E0 prior to fitting.
Michel Jauoen wrote:
I agree with Scott: SCF calculation gives more reliable estimate of E0 because the Fermi level is more accurate. It makes that, when several atomic species are involved, you only need in principle one E0 for fitting (I have verified this point, at least for the case I'm presently working on).
Interesting -- I haven't seen this effect, but I probably haven't looked very hard either. I don't think that having an E0 'closer to the experiment' is a significant gain, as it still is relative to the experimental E0 (which is usually the fairly ad-hoc max-of-derivative) and has to be refined in the fit. But if it can reduce the number of situations where you need 2 E0's, that could be important. I think it's still not well understood when multiple E0's are needed, but having some insight on where Feff8's SCF is noticeably better might be a good start. Would one of you be willing to send an example, and/or maybe give some indication of what sort of systems would need 2 E0's with Feff6 and 1 E0 with Feff8? Thanks, --Matt