[Ifeffit] How to change the data file in Dartemis?

Robert Gordon ragordon at alumni.sfu.ca
Thu Jul 7 18:59:25 CDT 2016


Hi Isabelle,

If I understand your emails correctly, you are trying to fit two 
variations of a dataset (with different normalisations)
to a given model FEFF calculation, yes? You have two different chi(k)'s. 
Rather than trying to replace.
have you tried:

Just fitting them one at a time in Artemis? i.e.  Import the first 
chi(k), set the FT parameters etc. Generate
the FEFF model. Pick paths.  Set the GDS values. Save the project file. 
Run fit. Discard first data, import second
set the FT parameters, select paths, enter the GDS values in the data 
window...(save again, perhaps as different
fpj) and fit again?  (OK...this is replace, but by brute force)

How about fitting both at the same time using the same FEFF model: 
Import both chi(k)'s and run two
independent fits (i.e. amp1 for 1st, amp2 for 2nd etc) with the same 
FEFF calculation?

I have tested both of these routes and they do work (though there is an 
issue with the Artemis [Plot] window
dropping one of the datasets if it isn't being fit).

regards,
-R.

On 7/7/2016 7:04 AM, Isabelle Kieffer wrote:
> Dear Bruce, dear all,
>
> Just to add some input and precise my question.
>
> The problem I encounter with "replace this chi(k)" did not appear to 
> me until I tried to fit a spectrum twice with two different 
> normalisations. In this case, after a fit on the first spectrum, I 
> "replace this chi" with another that is normalised differently, and 
> when I try to fit, it stops with the following error message:
>
>      This data came from the the same source as another
>      data group. You seem to be trying to increase your
>      number of independent points by fitting the same data
>      more than once in a multiple data set fit.
>
>
> Seeing that, I wondered whether "replace this chi" was doing what I 
> thought. The upgrade did not change anything. I just tried with a 
> colleague working under windows and the result is also the same.
>
> Shall I do differently to fit those two really similar spectra?
>
> Thank you for your help,
>
> Isabelle
>
>
>
>
> On 01/07/2016 21:08, Bruce Ravel wrote:
>> On 07/01/2016 01:57 PM, Isabelle Kieffer wrote:
>>> You mean that when you "Replace this chi(k)", it asks what to do, or it
>>> supposes that you want to fit new data with the same model?
>>
>> What I mean is: upgrade.  Many of the problems you are reporting have 
>> been fixed already.  If you upgrade and still see these problems, 
>> make a bug report and I will look into it.
>>
>> B
>>
>>
>



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