[Ifeffit] (no subject)

[Carlo Segre]

Hi Bindu:

I am presuming that you mean that you want to tune the bond angle of the 
MS paths in your EXAFS fitting but, as Bruce notes, I might be wrong.

The bond angles for the multiple scattering paths are simply calculated 
from the positions of the atoms around the central atom in the FEFF input 
file.  In the refinement process used by Ifeffit, the overall path length
is slightly changed to fit the experimental data.  This implies 
that a 3-Dimensional geometry has been reduced to a 1-Dimensional 
fitting and all angular information is locked into the initial 
FEFF calculation.  Thus you can only tune angles by starting with a 
different local arrangement of atoms around the central atoms.

To my knowledge, there is no automatic way of doing this but there are 
manual ways of approaching the problem depending on the kind of system you 
are studying.  It would be helpful to have more information.

Cheers,

Carlo

On Tue, 27 Nov 2007, Bindu R. wrote:

> could you tell me how does one tune the bond angles from the multiple 
> scattreing paths?
>
> Bindu
>
>
> Dr.Bindu R.
> Visiting Scientist
> DCMP&MS
> Tata Institute of Fundamental Research
> Homi Bhabha Road
> Colaba
> Mumbai-400 005
> India
> Mobile-919892536830
>
> ---------------------------------
> Chat on a cool, new interface. No download required. Click here.

-- 
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