Modulated Structures CIF Dictionary version 1.0

_geom_contact_site_ssg_symmetry_

Names

Category: geom_contact

Data type: char

Must appear in a looped list containing '_geom_contact_atom_site_label_'

Examples:

. 'no symmetry or translation to site'
4 '4th symmetry operation applied'
7_6455 '7th symm. posn;+a on x;-b on y'

Definition

    	

   The symmetry code of each atom site as the symmetry operation
   number 'n' and the higher-dimensional translation 'm1...mp'. 
   These numbers are combined to form the code 'n m1...mp' or 
   n_m1...mp. The character string n_m1...mp is composed as follows:
   'n' refers to the symmetry operation that is applied to the 
   superspace coordinates. It must match a number given in 
   _space_group_symop_ssg_id. 'm1...mp' refer to the translations 
   that are subsequently applied to the symmetry transformed 
   coordinates to generate the atom used in calculating the contact.
   These translations (t1,...tp) are related to (m1...mp) by the 
   relations m1=5+t1,...,mp=5+tp. By adding 5 to the translations, 
   the use of negative numbers is avoided. The number 'p' must agree
   with (_cell_modulation_dimension + 3). If there are no cell 
   translations the translation number may be omitted. If no 
   symmetry operations or translations are applicable then a single
   period '.' may be used.