[Ifeffit] Basic issues in EXAFS curve-fitting

Scott Calvin scalvin at slc.edu
Mon Jun 20 11:14:11 CDT 2005

Hi all,

I'm in the process of preparing a proposal for a project, part of which
will entail taking a practical look at basic issues in EXAFS curve-fitting
to theoretical standards. These issues are the kind of thing that are now
handled anecdotally; I'd like to do some careful studies of what the
benefits and drawbacks of various schemes in use really are. To keep this
from getting too broad, my focus is primarily on nanoparticle oxides (the
area where I've done the most work), but many of these questions will come
up while fitting a wide variety of materials.

Here are some examples of the kind of issues I'd like to consider:

Choosing a measurement uncertainty for computing chi-square
Multiple-scattering constraint schemes
Ei--is a non-zero value helpful in these fits?
Third cumulant--is a non-zero value helpful in these fits?
Nanoparticle size-determination schemes
Debye-Waller factor constraint schemes
Fourier transform issues (e.g. windowing)

I'd like to hear any suggestions any of you have for additions to this
list. Basically, I'm looking for issues that we all have to deal with in
routine fits, but are currently dealt with differently by different

--Scott Calvin
Sarah Lawrence College

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