Thank you for your answers,

I think there were several troubles on my analysis.

First of all i didn't understand well how the fuzzy degeneracy works but after your suggestion i read the JSR paper and now it is pretty clear.
Also, the fact that i was obtaining twice the same path list in the two sites was due to the mislabeling of the two Co sites (now it works!).

Thank you !

Eugenio

2015-04-09 22:04 GMT+02:00 Bruce Ravel <bravel@bnl.gov>:


Regarding the "Aggregate" button, it is important to understand what that button is trying to do.  It is a tool that is very easy to misuse, or at least get confused by.

You should read this page from the manual:

   http://bruceravel.github.io/demeter/artug/feff/aggregate.html

and this article:

   http://dx.doi.org/10.1107/S1600577514014982

If it's what you're looking for, cool.

B


On 04/09/2015 06:01 AM, Eugenio Paris wrote:
Hello everybody,

I'm trying to make Co K-edge EXAFS fitting for the Co3O4 compound (*.cif
file is attached). The nearest neighbour of Co is oxigen at about 1.93
Angstrom distance.
Cobalt sits in two inequivalent sites in the unit cell. When I perform
the FEFF calculation in Artemis for either one or the other site i get
the same path with Reff = 1.93 and degeneracy = 4.
So i wonder what is the correct way to take account of the presence of
both sites. At the beginning i was thinking to put 2*amp as S0^2
parameter to take account for twice the coordination number.
Then i tried to use the "Aggregate" option in Artemis. When I use this
option i get exactly the same result, i.e. a SS path with Reff = 1.92
and degeneracy = 4... I was expecting to get twice the degeneracy.. (the
margin and beta parameters are set to default)

My question is:
Why do i get the same path list when I do use the "Aggregate" pathfinder
and when I don't? What is wrong in my interpretation?

Thank you in advance!
Sincerely,
Eugenio


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--
 Bruce Ravel  ------------------------------------ bravel@bnl.gov

 National Institute of Standards and Technology
 Synchrotron Science Group at NSLS-II
 Building 535A
 Upton NY, 11973

 Homepage:    http://bruceravel.github.io/home/
 Software:    https://github.com/bruceravel
 Demeter:     http://bruceravel.github.io/demeter/

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