[Ifeffit] Possibly non-reproduceable fits

[Bruce Ravel]

Ian,

I am suspicious that the quick first shell paths are not getting saved 
correctly to the project file.  Or perhaps not getting restored 
correctly from the project file.

I'll look into it.  Since your description isn't exactly a recipe, I am 
going to have to do some testing to try to find the problem.

Perhaps the easiest work-around would be to not use the quick first 
shell tool.  For the Au-Au parts of the fit, using the crystal structure 
for the pure metal is simple.  For the Au-Ag, Ag-Au, and Au-Cl parts, it 
should be fairly simple to make a feff.inp file.  For the mixed metal 
parts, try replacing the entire first shell with the other metal.  For 
Au-Cl, try this: http://www.crystallography.net/cod/1510088.html

Thanks for the bug report -- I'll let you know if I figure anything out.

B

On 08/04/2015 12:00 AM, Godfrey, Ian wrote:
> Dear All,
>
>
> Please bear with me here - it's possible I've done something stupid
> without spotting it - but I was fitting some data in Artemis and have
> two fits, that I am convinced should be identical (same data, same k and
> r windows, same paths, same GDS etc. etc.), but are not.
>
>
> What I did was as follows (fit numbers refer to the Artemis history file
> in the attached project):
>
>
> I set up a fit to some data, simultaneously refining at Au and Ag edges
> to Au-Au/Au-Ag/Ag-Au/Au-Ag paths (fits 1 & 2), and then tried a
> different fit, this time with Ag-Cl paths as well (fits 3&4). I then
> fitted the original model again (fit 5  - this was slightly different to
> 1 & 2, but not enough for me to notice at the time). I then closed
> Artemis and finished for the day. Today I came back, reloaded the
> project file, saved it in a new location, and tried to pick up where I
> left off. I performed one fit where I'd set the values to def, rather
> than guess, by mistake (fit 6) and then corrected this when I realised
> what I'd done. However when I tried to re-run the model with Ag-Cl paths
> I was getting wildly different results to the first time (Fits 7&8). As
> far as I can tell these models should be identical to fits 3&4.
>
>
> Both datasets were chi(k) data imported directly into Artemis.
>
>
> OS: Win 8.1 Ent x64
>
> Demeter: 0.9.22 pre something x64
>
>
> I've attached the following:
>
>
> Artemis project (artemis.fpj)
>
> Logs from fits 3 and 7 for comparison (fit3.txt, fit7.txt)
>
> Artemis log file (dartemis.log).
>
>
> (Also possibly worth noting is that Artemis seems to have lost the file
> locations (in the log files and the data window), first for the Au edge
> data, and then for both datasets; however when I plot the data it all
> seems present and correct!)
>
>
> Any insight gratefully received!
>
>
> Thanks,
>
>
> Ian
>
>
> ----
>
> Ian Godfrey
>
> PhD Student,
>
> UCL/JAIST Programme
>
>
> Industrial Doctorate Centre in Molecular Modelling and Materials Science,
>
> Department of Chemistry,
>
> University College London
>
> and
>
> School of Materials Science,
>
> Japan Advanced Institute of Science and Technology
>
> i.godfrey at ucl.ac.uk <mailto:i.godfrey at ucl.ac.uk> i.godfrey at jaist.ac.jp
> <mailto:i.godfrey at jaist.ac.jp>
>
>
>
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-- 
  Bruce Ravel  ------------------------------------ bravel at bnl.gov

  National Institute of Standards and Technology
  Synchrotron Science Group at NSLS-II
  Building 535A
  Upton NY, 11973

  Homepage:    http://bruceravel.github.io/home/
  Software:    https://github.com/bruceravel
  Demeter:     http://bruceravel.github.io/demeter/