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Re: [magCIF] MagCIF in Jana2006

Dear Branton,

|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
|read) them.

I agree. Both definitions are already accepted by Jana2006 for reading but
for output we have to follow CheckCIF program which asks the new form.   

|2) The coreCIF definition of _atom_site_site_multiplicity suggests that it
|independent of centering and other setting transformations (standard or
|standard).  My interpretation of this definition is that one should always
|the site multiplicity of the conventional (not primitive) cell.  Do I
understand this

I understand your point. But for calculation of structure factors, density
and other global characteristics we prefer the definition of multiplicity as
a number of atoms generated from the actual atomic position by all  
symmetry operations including non-standard centering operations to get the
full cell contents.        

|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
|reversed operators as though they were normal operators.

I agree.

With best regards,

|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
|category separator '.' or '_'. The output from Jana uses the definition as
made by
|> 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
|been defined:
|> _atom_site_site_symmetry_multiplicity
|> _atom_site_site_symmetry_order
|> For more details see:
|> I think we should use the new definition.
|> Another problem connected with multiplicities of different atoms is that
|should decide what to use in cases when non-standard setting is used. Each
|additional non-standard centering vector multiplies the number of
|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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