Category SPACE_GROUP_SYMOP_MAGN_CENTERING

Name:
'SPACE_GROUP_SYMOP_MAGN_CENTERING'

Parent category:
MAGNETIC

Definition:

   
     This loop provides a list of centering or anti-centering
     translation in a BNS-supercell description of a magnetic space
     group.
     Keeping the centering and anti-centering translations in a
     separate loop leaves only representative point operations in the
     main SPACE_GROUP_SYMOP_MAGN_OPERATION loop. The direct sum of
     the two loops produces the full set of representative operations
     of the magnetic space group.  This centering loop is optional, so
     that it is always possible to include all of the symmetry
     operations in the main loop.
     When this centering loop is employed, the representative point
     operations in the main SPACE_GROUP_SYMOP_MAGN_OPERATION loop may
     not form a closed subgroup, but instead  generate some of the
     fractional translations of the centering loop.  Despite this
     annoyance, a separate centering loop is important because
     magnetic structures tend to have a relatively large number of
     centering and anti-centering translations, which can make the
     resulting list of operators very long and unintuitive, especially
     when working  in non-standard settings.
     One could argue that anti-centering operations belong in the main
     representative- point-operation loop since they are not actually
     translations of the magnetic lattice.   In fact, a pure time
     reversal is a generator of the magnetic point group of a  type-4
     magnetic space group.  Nevertheless, this centering loop is
     defined to  include the anti-centerings due to the common
     practice of referring to a "black and white" lattice of
     centerings and anti-centerings.

Example:

Category is of type Loop

Category key:
_space_group_symop_magn_centering.id