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Esfit fitting problem

Posted: Tue Mar 09, 2021 6:10 am
by arijithazari

Hi,
I am new to easyspin! I have been trying to fit epr data, however simulation of the parameters is taking way too long than expected and I have been getting following error after a while

'** Spectrum exceeds sweep range. Artifacts at upper limit possible.
** Spectrum exceeds sweep range. Artifacts at upper limit possible.'

Please suggests!

Thank you!


Re: Esfit fitting problem

Posted: Tue Mar 09, 2021 3:00 pm
by thanasis

You don't include the experimental spectrum, so we cannot run the script, but some comments can be made:
-The problem's Hilbert dimension is (2 * 1 + 1)*(2 * 3/2 + 1)2 = 48. It's not excessive, but it isn't negligible either.
-As for the message, during the fit some resonances appear outside your experimental range. This might not be a serious problem, but if you want to get rid of it maybe try a spectrum over a broader region.


Re: Esfit fitting problem

Posted: Wed Mar 10, 2021 1:34 am
by arijithazari

Hello,
Sorry, I forgot to attach the epr file, please find the attachment.
Thanks for the suggestion. But, I did try to run the simulation over wider experimental range. But I still have the same problem.

Thank you again.


Re: Esfit fitting problem

Posted: Wed Mar 10, 2021 3:50 am
by thanasis

Yes, overall it was slow, but not shockingly so. Remember, it is a powder spectrum, so you need to integrate over a large number of orientations. Maybe you can decrease the number of nodes on your spherical grid for the initial fits.

Also, I got no alert, though I did not let it turn for too many iterations. It may be that during the fitting process some iterations give parameters that lead to off-range resonances. I didn't see anything worrisome, though.


Re: Esfit fitting problem

Posted: Thu Mar 11, 2021 1:54 pm
by arijithazari

Ok, thank you very much for your suggestions. I have taken into account all the points now, it is running fine.