Crystallographic Information Framework

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Core dictionary (coreCIF) version 2.4.5




   A parsable string giving one of the symmetry operations of the
   space group in algebraic form.  If W is a matrix representation
   of the rotational part of the symmetry operation defined by the
   positions and signs of x, y and z, and w is a column of
   translations defined by fractions, an equivalent position
   X' is generated from a given position X by the equation

             X' = WX + w

   (Note: X is used to represent bold_italics_x in International
   Tables for Crystallography Vol. A, Part 5)

   When a list of symmetry operations is given, it must contain
   a complete set of coordinate representatives which generates
   all the operations of the space group by the addition of
   all primitive translations of the space group. Such
   representatives are to be found as the coordinates of
   the general-equivalent position in International Tables for
   Crystallography Vol. A (2002), to which it is necessary to 
   add any centring translations shown above the 
   general-equivalent position.

   That is to say, it is necessary to list explicitly all the
   symmetry operations required to generate all the atoms in
   the unit cell defined by the setting used.

               In order for the defaults to work correctly, the identity
               operation should have _space_group_symop_id or
               _symmetry_equiv_pos_site_id set to 1, and
               _space_group_symop_operation_xyz or
               _symmetry_equiv_pos_as_xyz set to x,y,z; 
               i.e. the operation labelled 1 should be the identity


x,1/2-y,1/2+z glide reflection through the plane (x,1/4,z), with glide vector (1/2)c

May appear in list containing _space_group_symop_id

Related item: _symmetry_equiv_pos_as_xyz (alternate)

Enumeration default: x,y,z

Type: char

Category: space_group_symop