Hi Carlos and Matt,
Matt is correct that the CFAVERAGE card averages over a variety of
absorbing atoms specified within the input file, with amplitude fixed to 1.
In addition, CFAVERAGE only works in FEFF8.4 and earlier, and only if you
have the monolithic version (i.e., feff is a single executable, not a
script that runs several executables). We intend to improve the
capabilities of feff9/jfeff to include more possibilities in terms of
averaging over the absorption of different sites within a feff.inp file, or
averaging over multiple input files, but for now, you will have to perform
the averaging yourself.
Cheers,
Josh Kas
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than "Re: Contents of Ifeffit digest..." Today's Topics: 1. Re: FEff (Matt Newville)
2. Trouble creating feff input file for NaTiO3 cubic perovskite
structure (Badari Rao)
3. Re: Trouble creating feff input file for NaTiO3 cubic
perovskite structure (Bruce Ravel) ---------------------------------------------------------------------- Message: 1
Date: Mon, 29 Sep 2014 12:47:57 -0500
From: Matt Newville On Mon, Sep 29, 2014 at 11:48 AM, Bruce Ravel On 09/29/2014 11:44 AM, Carlos Triana Estupinan wrote: Dear
Feff group I am Carlos Triana, and I want ask you the following.
I am trying to calculate the feff.inp file for a theoretical amorphous
structure composed by a supercell with 24 Ti atoms surrounding by 48
oxygen atoms with different coordination. In amorphous materials or
materials with distortions from regular crystals, the absorbing atoms
may have different surroundings.
My question is how can I build the feff.inp file in this case, shall I
define the 24 Ti atoms like absorbing atoms, because in this case the
feff does not works.
What can I do in this case, how can I build the feff.inp file with
different environments I will be very grateful for your help I'd like to follow up on Matt's comment. I presume you have some way of knowing a list of Cartesian coordinates
for
the atoms in your cluster. If so, the discussion on pages 7-10 of this
talk should be helpful, with the caveat that your input file needs to be
appropriate to the version of Feff you intend to use. https://speakerdeck.com/bruceravel/modeling-non-
crystalline-samples?slide=9 Make one input file for each Ti atom serving as the absorber. As Matt
said, take care not to overwrite your results. Were this my problem, I would prefer to organize and perform N
calculation, then add them up myself. That said, Feff does provide a
simple sort of configuration average. Look up "CFAVERAGE" in the Feff
document. B I believe CFAVERAGE does not work as advertised. I haven't checked this
recently, but my recollection is that using CFAVERAGE always ends up giving
a coordination number that is a whole number, which cannot always be the
case. That might depend on versions of Feff, and I'd be happy to shown to
be wrong about this. Can anyone else verify or shed light on this? --Matt