[Ifeffit] Error in Atoms output

Godfrey, Ian i.godfrey at alumni.ucl.ac.uk
Tue Mar 20 13:33:16 CDT 2018


Hi Bruce/All,


I've recently (before this bug was reported) done some monoclinic analyses; consequently, I'm wondering if this bug impacts all monoclinic CIFs, or only certain cases (and if so, is there any easy way to confirm whether it had an impact?)? I think my data was fine - the path list matched what I was expecting and what has been reported previously - but I'd like to be certain before publishing etc..


Thanks,


Ian

________________________________
From: Ifeffit <ifeffit-bounces at millenia.cars.aps.anl.gov> on behalf of Bruce Ravel <bravel at bnl.gov>
Sent: 27 February 2018 17:07:59
To: XAFS Analysis using Ifeffit
Subject: Re: [Ifeffit] Error in Atoms output

On 02/19/2018 06:23 AM, Kaustubh Priolkar wrote:
> We are trying to fit low temperature V K edge EXAFS data in V2O3. As per
> the cif files available (attached herewith – V2O3_10K data.cif) the
> structure is described by I2/a space group. When this file is read by
> ATOMS it gives an erroneous output ( attached herewith - feff.inp). In
> particular the values of V-O and V-V bond distances are not correct and
> do not match with bond distances reported in literature (Phys. Rev. B 2
> (1970) 3771).
>
> Could anyone tell me where am I making a mistake. I am aware that I2/a
> is a non standard space group but I am not sure if I need to take any
> precaution while reading the cif file in ATOMS.
>
> Thanks and regards,

Hi Kaustubh,

Thanks for this bug report.  This uncovered not one but two bugs in how
Atoms handles monoclinic space groups.  How economical!  I will be
pushing a fix to github soon and I will try to find some time to make a
new windows installer.

I should point out that, even with the bug fix, the distances using the
CIF file you attached will not match Phys. Rev. B 2 (1970) 3771.

The CIF file that you supplied is from
doi:10.1016/S0022-4596(03)00295-0, which reports slightly different
numbers for the undoped V2O3 compared to the 1970 paper.  I have
attached a feff.inp file that I think is correct.

B





--
  Bruce Ravel  ------------------------------------ bravel at bnl.gov

  National Institute of Standards and Technology
  Synchrotron Science Group at NSLS-II
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