[Ifeffit] Query regarding inequivalent sites in the EXAFS fitting

[Carlo Segre]

Hi Eckhard:

On Fri, 29 Feb 2008, s440697 at stud.uni-goettingen.de wrote:

> Hi,
> my normal proceeding is (for example Na_2 SO_4) to calculate with an
> atom-cluster of this substance with lots of atoms an lots of sulfur. I
> chose one as the absorber and make one single feff-run. But when i do this
> for all sulfur atoms consecutively (because in experiment every sulfur
> absorbs the x-rays of course) i have lots of single results in my several
> folders. Now the question:
>
> How can i combine this results meaningful? You said:
>> You will then be able to import the first path of each calculation into
> the >model.
> Where can i find the first paths? paths.dat, list.dat or feffNNNN.dat? And
> what do you mean with "import into the model"? Which model? Sorry, but i
> worked only with the command-line based FEFF 8.4
>

The original answer I gave was for EXAFS fitting using Artemis.  There, 
the individual was asking how to use the first shell paths from the two 
inequivalent positions in  crystal structure to develop a model for 
EXAFS.

My impression from your message was that you are more interested in doing 
XANES calculations with FEFF (perhaps I misunderstood...).  For the XANES 
calculations, you get output files with density of states and other 
information.  In order to obtain something that will simulate the 
experimental data that you obtain, you need to add all of these 
contributions together and then apply a Fermi function to properly 
simulate an edge.  There is probably a lot more that can be done but I am 
not an expert there.  For this kind of calculation, Artemis doesn't really 
help, command line invocation of FEFF8.4 is the only thing to do.

>
> Can you explain it please a little bit more in details?
>

The bottom line is that I was answering what I percieved to be two 
different questions, one EXAFS, the other XANES.  If I was incorrect, 
please let me know.

Cheers,

Carlo



-- 
Carlo U. Segre -- Professor of Physics
Associate Dean for Special Projects, Graduate College
Illinois Institute of Technology
Voice: 312.567.3498            Fax: 312.567.3494
segre at iit.edu   http://www.iit.edu/~segre   segre at debian.org