[Ifeffit] fitting

[shelly Kelly]

I agree. 

To see if the problem is at high k, just make three copies of the data and then ft it with larger values for kmax.  That would indicate noise as the problem.

You can do the same at low k by adjusting kmin. That would indicate a problem with the background.

You can find examples of these methods in my book chapter.  Send me an email and I'll send it to you.

Tht
Shelly



-- Sent from my Palm Prē
On May 13, 2010 4:53 PM, Stefan Mangold <stefan.mangold at iss.fzk.de> wrote: 

Hello,
to ideas coming into my mind without an look at your data:
1. Very noisy data ... (may produce to many peaks)2. problems with the background correction
regards
Stefan
Am 13.05.2010 um 23:34 schrieb María Elena Montero Cabrera:I don't know anything about CeO2, but...for me there is something wrong since the Athena fitting, because there are too many peaks below the main one, and specially below 1 A. Am I right or not?

Maria Elena 


2010/5/13 Frenkel, Anatoly <frenkel at bnl.gov>

There is a large number of articles explaining how to fit CeO2 including discussions why multi-electron excitatoins complicate the fit, and some of those authors (e.g., A. Soldatov, but also M. Benfatto) propose first principle methods that account for those.


Some papers even show that ignoring those contributions may give a decent fit, but you should be aware of the multitudes of theoretical issues surrounding EXAFS modeling of this system before trying it on your own.



Anatoly







________________________________



From: ifeffit-bounces at millenia.cars.aps.anl.gov on behalf of mohamed sobhy

Sent: Thu 5/13/2010 5:21 PM

To: ifeffit at millenia.cars.aps.anl.gov

Subject: [Ifeffit] fitting





Dear all

I am trying to use artemis to do fitting to CeO2. But really I cant get the right way to do that.

During the fitting, I am using amp as set and change in N degeneracy of the path. attached is the best fit i got but it still not good and the chi-square is 41.109065479

so can you suggest me what to do



thanks



Mohamed








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-- 
María Elena

Dra. María Elena Montero Cabrera
Departamento de Medio Ambiente y Energía
Centro de Investigación en Materiales Avanzados (CIMAV)
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Dr. Stefan Mangold
Institut für Synchrotronstrahlung
Forschungszentrum Karlsruhe
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