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Re: [magCIF] MagCIF in Jana2006

Dear Vaclav (and others),
[I apologize if you receive multiple copies of this message due to my email-server problems.]
1) The ISOTROPY suite currently use the older multiplicity/order tags.  But it will not be difficult to change to the new tags, especially since we only write (not read) them.
2) The coreCIF definition of _atom_site_site_multiplicity suggests that it is independent of centering and other setting transformations (standard or non-standard).  My interpretation of this definition is that one should always present the site multiplicity of the conventional (not primitive) cell.  Do I understand this correctly???
3) Because time reversal does not affect atomic coordinates, it has no effect on multiplicity.  The multiplicity of a given site is determined by treating time-reversed operators as though they were normal operators.
Best wishes,

On Jul 1, 2014, at 5:56 AM, Vaclav Petricek wrote:

> Dear all,
> Today I have finished a new version of Jana2006 which should read MagCIF files from MAGNDATA and ISODISTORT. Moreover the new definition helped me to considerably simplify the procedure for calling VESTA program from Jana2006. Now it uses directly MagCIF files for commensurate and also incommensurate cases.
> Generally the new version of Jana is accepting both definitions using as the category separator ‘.’ or ‘_’. The output from Jana uses the definition as made by Branton.      
> I have several notes concerning the tag:
> _atom_site_symmetry_multiplicity
> As this tag was used in different programs in different way two new tags have been defined:
> _atom_site_site_symmetry_multiplicity
> _atom_site_site_symmetry_order
> For more details see:
> http://www.iucr.org/__data/iucr/cifdic_html/1/cif_core.dic/Iatom_site_symmetry_multiplicity.html
> I think we should use the new definition.  
> Another problem connected with multiplicities of different atoms is that we should decide what to use in cases when non-standard setting is used. Each additional non-standard centering vector multiplies the number of equivalent atomic positions by two except of for the pure time inversion (0,0,0,-1) and the time inversion combined with 1/2 shift in x4 (0,0,0,1/2,-1) for modulated structure. This is the reason why Jana2006 is sometimes complaining about multiplicities when some MagCIF files are imported.
> With best regards,
> Vaclav
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