[Ifeffit] Using Larch to analyze uranium compounds

[Matt Newville]

Hi Juejing,

Sorry for the trouble. It's hard to guess from the screenshots alone - if
only we had a Project file you could send (soon, soon).

One thing I see is it looks like the Feff calculation you're using was done
at the U K-edge.  Is that correct?  Is the data U K-edge too?

I don't know if that would completely explain the difference, and Mike's
suggestion of looking at the coordination number is a good idea.

XAS Viewer writes a "feffit script" in your user folder
(C:\Users\jiuju\larch\xas_viewer\feffit_script.lar).  Compared to the GUI
form, that's a little bit cryptic and formal, but it is also what the
program is really doing.  If the suggestions above don't help clarify the
problem, can you post that?



On Fri, May 20, 2022 at 7:35 PM <juejing.liu at gmail.com> wrote:

> Hi,
>
>
>
> I am recently trying to use Larch to fit XAS spectra of uranium compounds
> (e.g., UO2, using an existing CIF file). I did not achieve a good fit and
> the amplitude of the model is way lower than the data. Then I tried to plot
> the uranium oxygen 1st path with all 8 atoms a sigma2=0.001 by using the
> plot model function. The resulting scattering peak is still far lower than
> it should be (images below). Did I do something strange with the program?
>
>
>
> The Larch version I used was 0.9.59. I can send the cif file and the UO2
> data I used if necessary.
>
>
>
> Best,
>
>
>
> Juejing
>
>
>
>
>
>
>
>
>
> *Juejing Liu*
>
> Guo Group
>
> Materials Science and Engineering program
>
> Alexandra Navrotsky Institute for Experimental Thermodynamics
>
> Washington State University
> Pullman, WA  99164-4630
> Office: Fulmer Hall, Room 630
> Phone: 208-206-7304
>
>
>
>
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--Matt
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