[Ifeffit] Comparison of "amp" between Feff8.40 and feff6 - Curved waves or Plane waves?

Scott Calvin SCalvin at slc.edu
Fri Aug 29 14:48:05 CDT 2008

Hi Ying,

I haven't tried your project files, but in general paths are sorted by  
reff. IFeffit makes no assumptions, however, about how paths have been  
sorted; by importing paths from different FEFF calculations, for  
instance, you can end up with different orders without a problem.

Different versions of FEFF may sometimes number paths differently,  
though, primarily because the criteria for throwing out unimportant  
paths may be different. So it's important when comparing to make sure  
that you're actually using paths that represent the same scattering,  
and not just paths that are numbered the same.

--Scott Calvin
Sarah Lawrence College

On Aug 29, 2008, at 1:54 PM, Ying Zou wrote:

> Dear all,
> Nice to get so prompt response from Bruce and Scott, thanks for  
> their effort to make this list vital!
> Looks like "amp" is a factor which can be reduced. Then there is a  
> question: how would all paths be sorted? by Reff or by "amp"? More  
> techically related another question is then: can FEFFIT and FEFF  
> work seamless together on this? Is there any presumption in FEFFIT  
> (or more explicityly, ARTEMIS/ATHENA) which assumes all the paths  
> have been sorted by descending "amp" down from 100% with ascending  
> The background story behind this: using the same structural model  
> (thanks Bruce!), I tried to fit either use paths from FEFF840 or  
> from FEFF6. The fitting with FEFF6 paths does a quite good job,  
> giving a R_factor~1%, reduced chi square~ 90. Yet the one with  
> FEFF840 paths terminates abnormally because two parameters cannot be  
> determined.
> Attached please find two ARTEMIS project files. And appreciate for  
> comments!
> Ying

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