[Ifeffit] Generating single scattering paths in Artemis

[Frenkel, Anatoly]

 <<feff.inp>> 
Hello Carlo et al,

FEFF6 allows to use SS cards that were specifically designed to
calculate single-scattering paths in the case the structural details are
not known, as in Carlo's case. I am attaching a working example where I
used to calculate single scattering FEFF in Cu-O in octahedral
coordination in Cu2+[H2O]6 complex. I included hydrogen in the input
file since it affects charge on oxygen, but in principle it works. Some
details are given in this article:
http://pubweb.bnl.gov/people/frenkel/HUMIC-EXAFS/est.pdf

You can run FEFF6 using attached file and note that it produces three
files, each corresponds to the single shell of Cu-O atoms. Note the use
of the OVERLAP card in the attached file, as well as the use of Bohr's
radius to work around the bug in FEFF6 that uses distances in OVERLAP as
multiples of Bohr's radius instead of Angstrems, while the units in SS
card are in Angstrems. 

Regards,

Anatoly

Anatoly Frenkel, Ph.D.
Associate Professor
Department of Physics
Yeshiva University
245 Lexington Avenue 
New York, NY 10016
http://www.yu.edu/faculty/afrenkel

    Office:
tel. (212) 340-7827
fax (212) 340-7788
anatoly.frenkel at yu.edu

    Laboratory: 
tel. (631) 344-3013
frenkel at bnl.gov


-----Original Message-----
From: ifeffit-bounces at millenia.cars.aps.anl.gov
[mailto:ifeffit-bounces at millenia.cars.aps.anl.gov]On Behalf Of Barton,
David (DG)
Sent: Wednesday, January 05, 2005 4:46 PM
To: 'XAFS Analysis using Ifeffit'
Subject: RE: [Ifeffit] Generating single scattering paths in Artemis


Scott,

> This can be fixed by editing the feff.inp file to remove the 
> Fe potential 1, but that's not enough--the oxygen scatterers 
> then have to have their potential renumbered to 1 to make 
> things work. That's a lot of work to do what should be simple.
> 
> So I vote for changing the way Artemis works in such 
> circumstances so that less editing is needed: if the 
> absorbing atom is not present in the scattering list, then it 
> shouldn't have a second entry in the potential list.
> 

I second this vote, since I also have had this same problem.  New users
could become quickly disgruntled by the Fatal Error message when
attempting to put in simple systems or just by choosing a short cluster
distance to only include the first shell in the FEFF calculation.  At a
minimum, it would be nice if Artemis trapped this error and reported a
more friendly popup error message.  


Dave
  _________________________________ 
  David Barton, PhD.
  The Dow Chemical Company 
  Catalysis R&D 
  
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