[Ifeffit] schemes for delr and sigma2 for multiple scattering paths

[Jatinkumar Rana]

Dear all,

It is reasonable to assign a constant fraction by which unit cell 
expands at a given temperature of XAFS measuremnt and so the variation 
in the path lengths for every single scattering paths could be assigned 
as delr = alpha * Reff. Similarly, one can assign  sigma2 value for each 
single scattering path depending on both type of scatterer and its 
distance from the absorbing atom.

Now coming to multiple scattering paths, Sigma2 for multiple scattering 
paths can be constrained based on the sigma2 of related single 
scattering paths and a definite path-geometry-dependent scheme 
(Triangle, collinear, reversed etc.) could be applied.

Is there any such scheme for delr of multiple scattering paths ? or we 
can simply assume that all paths (single scattering and multiple 
scattering) undergo uniform expansion by a factor alpha.

Thank you so much in advance for your valuable time...

With best regards,
Jatin Rana