Zhaomo Tan,
I think you have to set the path degeneracy to 1 because the model
you used for Cu in Artemis has already found that there are 12
degenerate paths which make up the first scattering distance. By
setting it to one, you then create a fitting parameter for the
coordination number CN. You also must constrain the amplitude
factor SO2 to some value because these parameters, N and SO2, are
correlated.
SO2(somewhere between 0.8-1.0) * N (=1) * CN(guess parameter)
- Chris
********************************
Christopher J. Patridge, PhD
NRC Post Doctoral Research Associate
Naval Research Laboratory
Washington, DC 20375
Cell: 315-529-0501
On 12/26/2012 6:23 AM, Zhaomo Tian wrote:
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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