[Ifeffit] What does FEFF stand for?
Matt Newville
newville at cars.uchicago.edu
Tue May 10 16:15:06 CDT 2011
I think Scott is right that the original meaning of "effective" was
that the scattering amplitude is not for point scattering of a plane
wave, as was used in earlier work (say, Sayers, et al 1971). Feff3
(circa 1990) didn't to do multiple scattering, but did put in curved
wave effects.
http://leonardo.phys.washington.edu/feff/Docs/feff3.html
But once you move away from the point scattering of plane waves,
"effective" can fold everything else in. So now "effective" does
include mapping the MS paths to a SS formalism does make more
"effective" (less native point-scattering of plane waves). The fast,
clever matrix representation for MS paths of Rehr and Albers was
incredibly important for making the calculations actually useful. I
believe others (Schaich? Gurman?) were calculating MS on triangles and
4-legged focused paths somewhat before Rehr, but that it was slow and
hard to generalize. Feff5 generalized this for all orders.
--Matt
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