[Ifeffit] Using radius in FEFF to determine nanoparticles

[Anatoly I Frenkel]

Lisa,

The number of papers using FEFF to model nanoparticles is in the thousands.
Starting with FEFF8, most XANES features can be reliably modeled.
Look for papers by J.Kas and others from J.Rehr group for details.

Neighboring nanoparticles do not contribute, one reason being that XAS is dominated by the interior of the particle, and there are many other reasons, but that one is the most important. 
Too few atoms on the first particle will see the atoms on the second particle to make contribution to average XAS. These contributions will be also strongly disordered and tend to cancel each other.

Anatoly


Sent from my iPad

On Sep 11, 2013, at 10:57 AM, "Lisa Bovenkamp" <lbovenkamp at lsu.edu> wrote:

> Hey all,
> 
> I started working on modelling nanoparticles with FEFF.
> 1. Anybody have some useful links about this subject?
> 
> 2. In 2 reports people were using the radius (i.e. number of atoms 
> used in the calculations) as a measure for the size of the nanoparticles.
> Further they were discussing the absence of features due to the
> size.
> This strikes me odd. I thought that for 
> a) a small SCF radius the feff code might not converge (which cannot give good results),
> b) when the FMS radius is small - and there are not many scatterers included - 
> the resolution of the calculated XANES spectrum is "bad" and features are broad.
> I think that has nothing to do with the nanoparticles
> c) a correct real space feff table of xyz coordinates should include more than just one 
> nanoparticle since the neighboring particles do have an effect on each other - or am I wrong?
> 
> Thanks.
> Lisa
> 
> 
> 
> 
> _______________________________________________
> Ifeffit mailing list
> Ifeffit at millenia.cars.aps.anl.gov
> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
>