Dear Konstantin, why would you want to do that? If you change the distance between A-B you the distance between B-A changes by the same amount. If you move the absorber away from let's say the centre of an octaeder you would split the (next) nearest neighbours shell into different shells with different distances. If the differences are large enough and the resolution of your EXAFS spectrum sufficient you would see more than one (first neighbours) peak in the FT of your EXAFS spectrum. But that would be another model that you would feed into FEFF before you start your second fit. Technically you would fneed to define the position of all atoms in your model in world-coordinates. So the absorber would no longer be at 0,0,0. I would guess that this would make the computation and the model more complex or at least less intuitive. Best regards, Edmund On 06.10.23 10:09, bikov@phys.uni-sofia.bg wrote:
Dear all, I have a general question regarding the mechanism employed in the fitting procedures implemented in Artemis. How exactly is performed a fit? Do we have a fixed central atom (absorbing/emitting atom) and only the distances to the neighbors included in the probed pathways are varied, i.e. by varying the coordinates of the corresponding neighbor atoms, or during the fitting process Artemis can vary the position of the absorption center too? Could the procedure be constrained in such a way that the scattering pathways are adjusted by only varying the coordinates of the central atom?
With kind regards, Konstantin Bikov PhD Student at the Physics Department of the University of Sofia, Bulgaria
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