# [Ifeffit] The degeneracy and the coordination number

Ravel, Bruce bravel at bnl.gov
Thu Dec 27 07:52:30 CST 2012

```Go the archives for this mailing list: http://www.mail-archive.com/ifeffit@millenia.cars.aps.anl.gov/index.html

Enter the words "coordination" and "degeneracy" in the box at the top of the page, then click the button labeled "Search".

I suspect the answers from the many times this question has been asked before will be helpful to you.  For example, this post from Scott -- http://www.mail-archive.com/ifeffit@millenia.cars.aps.anl.gov/msg03435.html -- in response to a thread on this very topic -- is quite helpful.

If it's still not clear, then ask again about the part that remains confusing to you.

Cheers,
B

________________________________________
From: ifeffit-bounces at millenia.cars.aps.anl.gov [ifeffit-bounces at millenia.cars.aps.anl.gov] on behalf of Zhaomo Tian [zhaomo1989 at postech.ac.kr]
Sent: Wednesday, December 26, 2012 6:23 AM
To: ifeffit at millenia.cars.aps.anl.gov
Subject: [Ifeffit] The degeneracy and the coordination number

Dear all,

I am confused about the degeneracy and the coordination number used in the Artemis program.
I want to get the coordination number of 1st shell of my copper sample, so I set a guess number N1=12(initial guess) as the coordination number which will vary during the fitting iteration, but when I am looking at the 1st path's parameters, there is another N appear which may stand for the degeneracy.The 1st path of copper model is single scattering, so the degeneracy N equals coordination number . But when I set N=12, the guessed N1 will have a value which is closed to 1, only when I set N=1, the guessed N1 will have a value which is closed to 12. It seems that N and N1 are reciprocals. But I think N actually equals N1 in the single scattering case.

So I am really confused, If I want to get coordination number of a shell in a fitting, how can I deal with floated coordination number and its path degeneracy N?

Thanks so much.

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