[Ifeffit] Questions for Artemis fit

[Matt Newville]

On Mon, Aug 18, 2014 at 7:45 PM, 이국승 <lks3006 at postech.ac.kr> wrote:

>   Dr Newville,
>
> Thank you for your reply.
>
> My first question is that I did not find the atoms.inp file in the demeter
> installer. If that is true, where can I get the atoms.inp file?
>
You might find what you're looking for at
http://cars9.uchicago.edu/~newville/adb/search.html    Metallic Au (fcc) is
there.

> Anyway, I did copy and paste the atoms.inp file of an old version of
> Artemis from my colleague's PC. I followed the Artemis intruction video for
> fitting Au foil data.
>

Hmm, it seems likely that you missed a step.

> I filled the crystal lattice information, run atoms, and Feff calculation.
>
Did you import and define a Path after doing this calculation?  Did you
define Path Parameters and variables for this fit?

> Finally I clicked the Fit button and I got the error message that I
> attached. Now here is my second question. What can I do to successfully Fit
> without errors? Do you have any idea from the error message?
>
It indicates that you have defined variables to refine in the fit ('amp',
'enot', and so forth) but not explained how those variables should alter
the EXAFS signal.   You'll probably want to use these in the Path
Parameters for the first shell Au-Au scattering.  But, you are doing the
analysis, so the most important thing is that you understand how the
variables you are asking to be refined actually effect the EXAFS signal.
These error messages are a feature of the program to remind you that you
need to understand the model you are using for the EXAFS signal.

So,  what do you intend 'amp', 'enot', 'delr', and 'ss' to do?    If you
don't know, go back and review the tutorial information.  The goal is not
to get a fit, the goal is to understand what the fit results mean.

Another question (it might seem random, but it is not):  what is your
fitting range?

--Matt

PS: to be clear, these are not rhetorical questions.  If you feel the need
to respond, please actually think about and answer all questions above.
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