[Ifeffit] (no subject)

Carlo Segre segre at iit.edu
Tue Nov 27 08:33:20 CST 2007

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.



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.
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Carlo U. Segre -- Professor of Physics
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Illinois Institute of Technology
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