[Ifeffit] Some questions regarding running Larch code in Python

Hanyu Zhang hxz269 at case.edu
Mon Jan 8 10:55:54 CST 2018


Hello everyone,

I'm trying to find radial distribution functions for materials with known
concentrations of individual atoms by running Larch code through Python,
but am having some difficulties with creating feffpaths:

   1. I'm not quite understanding the feff.inp files stuff. Calling
   FeffRunner().run() with a input file that works with Atoms always throws
   the "rdinp not found exception". From what I'm understanding,
   feffrunner().run() calls the different modules to create a feffpath()
   group, but where are the rdinp, pot, xsph, etc codes/files?
   2. Somewhat on the same line of thought, can someone give me an example
   of a valid feffNNNN.dat file to generate a feffpath() group? I went
   through feffdat.py and the parsing code in lines 88-102 (under __read())
   looks like it only accepts very specific input formats.
   3. What does "ipot" stand for in the "geom" variable? I understand that
   if I did pass in a valid file, I'd probably not have to know this, but I
   was just curious...

Also, this might be a overly-general question, but is this the best way to
approach the problem? The basic idea now is to get chi(k) values for a
bunch of different paths/RDFs, and figure out which ones match experimental
values the best. This is also the main reason I want to get past the
Demeter GUI and Larch-specific interface: eventually I might throw the code
on a supercomputer of some sort and have it crunch the numbers. The details
still have to be worked out on my end, but I was wondering if there was a
faster or better way to go about finding the RDF for compound materials
with known concentrations of individual atoms.

I've attached some of my Python code (with more specific versions of
questions 1 and 2 inserted as comments) and the feff.inp file I've been
testing with. (Simple file from http://cars9.uchicago.edu/~
newville/adb/search.html) I'm currently an undergrad exploring the field of
XAFS, so sorry in advance if there is something obvious that I'm missing...
Also, let me know if any clarifications are needed.

Thank you for your time and sorry about the email being so long,
Alice
----------
Hanyu (Alice) Zhang
CWRU Class of 2018 | Engineering Physics major
BS/MS program | Materials science
*Minors:* Mathematics | Materials science
*Honors societies:* National Society of Collegiate Scholars | Tau Beta Pi | Pi
Mu Epsilon
*Active Clubs:* Case Origami Circle | Case Rocket Team | CWRUbotix | Case
Physics and Astronomy club | Math club
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