[Ifeffit] problem with E0 (enot) parameters

[Matt Newville]

Hi Dariusz,

Just to follow up on Stefan's request to not post large attachments to email:

The ifeffit web page is a wiki, and would be an ideal place for
posting the data (feff inputs, project files, images of plots) for
such questions.  You can read up on the wiki page for how to do create
pages and post attachments.   I'd encourage anyone with similar
impulses to post large files to use the wiki for such discussions.

To follow up on the rest of your questions and this thread:

I agree with Jeremy's advice / observation that having an E0 shift
push E0 "over the white line"  is not so unusual when using Feff6,
especially for L3 edges.   I'm not sure there's a good reason for it
besides "Feff6 makes approximations".

I'd also add a few other points:
  1.  In your original post, you had a huge number (30!) of variables.
 I'd recommend that you start much more simply than that.  In
particular, I'd suggest starting without refining the background.
  2.  As you know, It's hard for EXAFS to distinguish between C, N,
and O backscatters, and so "flipping atoms" around to positions that
are "obviously incorrect but consistent with the EXAFS data" is
something you'll need to look out for, especially with so many
variables (see point 1).
  3.  My understanding is that W L3 is particularly hard.  If you
haven't already done so, I'd suggest checking the literature on this
and doing as many sanity checks as possible.

--Matt