[Ifeffit] Possibly non-reproduceable fits

Godfrey, Ian i.godfrey at ucl.ac.uk
Mon Aug 3 23:00:54 CDT 2015

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!




Ian Godfrey

PhD Student,

UCL/JAIST Programme

Industrial Doctorate Centre in Molecular Modelling and Materials Science,

Department of Chemistry,

University College London


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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