[Ifeffit] FEFF calculation for two inequivalent absorbing sites

[Robert Gordon]

Hi Eugenio,

Quick question: Did you change the tags for the Co atoms so that they are
different?
If I do that, I get 4 and 6 coordinate results. you can import the cif file
twice, run atoms on both
sites (with tags different) and get the two feff inputs for running.

-R.

On Thu, Apr 9, 2015 at 5:01 AM, Eugenio Paris <eugenio.paris at gmail.com>
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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