[Ifeffit] difference of feff interpretation generated by different version of artemis

[w***@126.com]

Hello, everyone. I recently ran into an issue in using Artemis software.

I used two versions of Artemis (Artemis 0.8.012 and Demeter 0.9.25) to generate the paths from the same input file (FeS2.inp), but there is big difference between the two path results.

e.g. 1, the path4 and path6 generated in Demeter 0.9.25 are not generated in Artemis 0.8.012, though they have a very low applitude.

e.g. 2, the path7 in Demeter 0.9.25 is likely identical to path5 in Artemis 0.8.012 judging from the degenracy, reff, and amplitude, but their scattering name are different: (+)-S1-S2-(+) in Demeter 0.9.25 and (+)-S2-S1-(+) in Artemis 0.8.012. In my opinion, the scattring sequence of photoelectron in multiple scattering affect the paramters of paths. Why do these two paths have different scattering sequence? Thanks very much for your help.



Qiang Chang
Institute of Coal Chemistry, CAS
Leyuan South II Street 1, Yanqi Development Zone
Huairou District, Beijing, POB. 101407
P.R. China
Email: ***@163.com

[Ravel, Bruce]

As I have said before, that's a feature, not a bug.

http://bruceravel.github.io/demeter/documents/Artemis/extended/fuzzy.html

B

Post by w***@126.com
Hello, everyone. I recently ran into an issue in using Artemis software.
I  used two versions of Artemis  (Artemis 0.8.012 and Demeter 0.9.25) to
generate the paths from the same input file (FeS2.inp), but there is big
difference between the two path results.
e.g. 1, the path4 and path6 generated in Demeter 0.9.25  are not
generated in Artemis 0.8.012, though they have a very low applitude.
e.g. 2, the path7 in Demeter 0.9.25 is likely identical to path5 in
Artemis 0.8.012 judging from the degenracy, reff, and amplitude, but
their scattering name are different: (+)-S1-S2-(+) in Demeter 0.9.25 and
(+)-S2-S1-(+) in Artemis 0.8.012. In my opinion, the scattring sequence
of photoelectron in multiple scattering affect the paramters of paths.
Why do these two paths have different scattering sequence? Thanks very
much for your help.
------------------------------------------------------------------------

Post by w***@126.com
Qiang Chang
Institute of Coal Chemistry, CAS
Leyuan South II Street 1, Yanqi Development Zone
Huairou District, Beijing, POB. 101407
P.R. China

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--
Bruce Ravel ------------------------------------ ***@bnl.gov

National Institute of Standards and Technology
Synchrotron Science Group at NSLS-II
Lead Beamline Scientist, 06BM (BMM)
Building 743, Room 114
Upton NY, 11973

Homepage: http://bruceravel.github.io/home/
Beamline: https://www.bnl.gov/ps/beamlines/beamline.php?r=6-BM
Software: https://github.com/bruceravel
Demeter: http://bruceravel.github.io/demeter/

[Matt Newville]

Hi Qiang,

Post by w***@126.com
Hello, everyone. I recently ran into an issue in using Artemis software.
I used two versions of Artemis (Artemis 0.8.012 and Demeter 0.9.25) to
generate the paths from the same input file (FeS2.inp), but there is big
difference between the two path results.

Well, maybe not a "big difference". But, it might be reasonable to expect
slightly different results from different versions of the code.

Post by w***@126.com
e.g. 1, the path4 and path6 generated in Demeter 0.9.25 are not
generated in Artemis 0.8.012, though they have a very low applitude.

Feff has an option to not generate path data from paths with "too low an
amplitude". What that means in detail depends slightly on the versions of
the program used. And Artemis may have changed the settings it passes to
Feff as well.

You attached the input to Atoms, and the results from Feff, but not the
input to Feff. Those are probably slightly different in the two versions.

Post by w***@126.com
e.g. 2, the path7 in Demeter 0.9.25 is likely identical to path5 in Artemis 0.8.012
judging from the degenracy, reff, and amplitude, but their scattering name
are different: (+)-S1-S2-(+) in Demeter 0.9.25 and (+)-S2-S1-(+) in Artemis 0.8.012.
In my opinion, the scattring sequence of photoelectron in multiple
scattering affect the paramters of paths. Why do these two paths have
different scattering sequence? Thanks very much for your help.

Scattering paths that are simply reversed (Absorber-> S1 -> S2 -> Absorber
vs Absorber -> S2 -> S1 > Absorber) are equivalent.

--Matt