Hello, Questions from a beginner in EXAFS...using Athena and Arthemis
From where to get the error bars for number of neighbours, distance and sigsqr (ss)?
What are Chi-square,Reduced Chi-square and R-factor and how should be their values in a fit? Sometimes it happen that "R-factor for this data set" does not have the same value as the first R-factor from results. Why? many thanks, Elena
Hi Elena,
From where to get the error bars for number of neighbours, distance and sigsqr (ss)?
I'm not sure whether you are asking where the error bars are reported or how they are determined. They should be reported in the Fit Summary window that pops up after the fit. The calculation is a bit more involved, and is described in the Feffit manual.
What are Chi-square,Reduced Chi-square and R-factor and how should be their values in a fit?
Does this help? http://cars9.uchicago.edu/cgi-bin/ifeffit/faqwiz?req=show&file=faq08.013.htp If not, maybe I'm not understanding the question.
Sometimes it happen that "R-factor for this data set" does not have the same value as the first R-factor from results. Why?
For a fit with more than one data set, the fit to one data set might be better than the fit to another data set. In that case the partial R-factors would be different. If that's not enough, please ask again. --Matt
Thank you Matt, For sure I have to read Feffit manual, I did not know that there is a manual. Regards, Elena
On Sunday 01 May 2005 15:54, Elena Ion wrote:
Thank you Matt,
For sure I have to read Feffit manual, I did not know that there is a manual.
There is a lot of documentation available about the software and about XAFS in general at the Ifeffit home page, on the home page for Athena and Artemis, at the Ifeffit FAQ -- frequently asked questions -- list (http://cars9.uchicago.edu/cgi-bin/ifeffit/faqwiz), and at this very useful web page (http://cars9.uchicago.edu/xafs/). B -- Bruce Ravel ----------------------------------- bravel@anl.gov -or- ravel@phys.washington.edu Environmental Research Division, Building 203, Room E-165 Argonne National Laboratory phone and voice mail: (1) 630 252 5033 Argonne IL 60439, USA fax: (1) 630 252 9793 My homepage: http://feff.phys.washington.edu/~ravel EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/
Thank you Bruce,
This link http://cars9.uchicago.edu/cgi-bin/ifeffit/faqwiz is exactly what
need a beginner.
Many thanks,
Elena
----- Original Message -----
From: "Bruce Ravel"
On Sunday 01 May 2005 15:54, Elena Ion wrote:
Thank you Matt,
For sure I have to read Feffit manual, I did not know that there is a manual.
There is a lot of documentation available about the software and about XAFS in general at the Ifeffit home page, on the home page for Athena and Artemis, at the Ifeffit FAQ -- frequently asked questions -- list (http://cars9.uchicago.edu/cgi-bin/ifeffit/faqwiz), and at this very useful web page (http://cars9.uchicago.edu/xafs/).
B
-- Bruce Ravel ----------------------------------- bravel@anl.gov -or- ravel@phys.washington.edu Environmental Research Division, Building 203, Room E-165 Argonne National Laboratory phone and voice mail: (1) 630 252 5033 Argonne IL 60439, USA fax: (1) 630 252 9793
My homepage: http://feff.phys.washington.edu/~ravel EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/ _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
participants (3)
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Bruce Ravel -
Elena Ion -
Matt Newville