Re: [Ifeffit] LCF on Larch - EXAFS Region

This is interesting. Could you say more about your skepticism of the robustness of EXAFS LCF, Matt? To be fair, it suffers from many of the same drawbacks of XANES LCF, plus others. But I'm curious about your thoughts on it since yours seems to be what amounts to a "strong opinion" on the subject.

On Aug 9, 2018, at 12:56 PM, Matt Newville wrote:

Hi Garret,

...

On Thu, Aug 9, 2018 at 12:27 PM Garret Bland wrote: Hello!

I've recently been trying to use Larch instead of Athena for EXAFS analysis, and I mainly do linear combination fitting for my samples. It seems that the XANES fitting is doing just fine requesting a specified region to fit (-25 to +75 eV). When I try to fit in the k-space however, Larch does not request a specific region in k space. I try to input the eV values corresponding to the k value I want to fit, but it is still plotting in mu rather than k . Is there anyway I can change this and/or do it manually on the larch GUI? Any help would be appreciated!

You're right that linear combinations in k-space are not really working in Larch's XAS Viewer, including that the range can only be set in energy. Much of XAS Viewer is fairly new -- I think it is fairly complete, but there are a few missing parts. I don't ever do linear combinations of chi(k) myself and am slightly skeptical that they are robust, so they've haven't surfaced to the top of the ToDo list yet. Any help would be greatly appreciated.

--Matt

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