[Ifeffit] Atoms and Feff for CuFe2O4 structure
Kevin Jorissen
kevinjorissenpdx at gmail.com
Sun May 4 16:59:27 CDT 2014
We used to say that FEFF will run on any input, but we've been proven wrong
several times :p.
Kevin Jorissen
On Sun, May 4, 2014 at 2:41 PM, Bruce Ravel <bravel at bnl.gov> wrote:
>
> The first hit for spinel MgAl2O4 at crystallography.net gives these
> coordinates:
>
> Mg1 Mg2+ 8 a 0. 0. 0. 1. 0 d
> Al1 Al3+ 16 d 0.625 0.625 0.625 1. 0 d
> O1 O2- 32 e 0.375 0.375 0.375 1. 0 d
>
> That's completely different from what's in the CIF file you sent. Your
> cif file does not have Cu or O at symmetry positions associated with a
> spinel. I suppose that makes sense given that your CIF file does not use
> the spinel space group.
>
> It is true that Feff crashes, taking Artemis with it, when you try to run
> it on a list of atoms which has atoms that are 0.09 Angstroms apart. I
> suppose that Artemis should recognize that situation and ask whether you
> really want to run Feff with such ridiculous input. I'll put that on my to
> do list.
>
> None of that answers your question of what to do. You have some crazy
> structure that comes from who-knows-where, that is not a spinel, but which
> you think is a spinel. I don't know what advice you are looking for, but
> you need to figure out your structure and make sure it runs to sensible
> completion in Atoms.
>
> B
>
> On 04/30/2014 01:55 PM, Qasim Imtiaz wrote:
>
>> Dear all,
>>
>> I am using Atoms to calculate a Feff input file for CuFe2O4 spinel.
>> However running Atoms/Feff results in program crash owing to 'two atoms
>> very close together'. I modified the .cif file before importing (owing
>> to partial occupancy issue) as following:
>>
>> Deleted: Fe2 Fe3+ 8 d 0.5 0.25 0.125 . 0.5 0
>> Modified: Cu1 Cu2+ 8 d 0.5 0.25 0.125 . 0.5 0 to Cu1 Cu2+ 8 d 0.5 0.25
>> 0.125 . 1 0
>>
>> After importing the file in Atoms, I also used different shift vectors
>> (e.g. -0.125 -0.125 -0.125) but the issue is not resolved. Can someone
>> help me please to solve this problem? Thanks.
>> Best Regards
>>
>> Qasim
>>
>>
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>
> --
> Bruce Ravel ------------------------------------ bravel at bnl.gov
>
> National Institute of Standards and Technology
> Synchrotron Science Group at NSLS --- Beamlines U7A, X24A, X23A2
> Building 535A
> Upton NY, 11973
>
> Homepage: http://xafs.org/BruceRavel
> Software: https://github.com/bruceravel
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