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Core CIF Dictionary version 2.3



'_geom_angle_site_symmetry_1' '_geom_angle_site_symmetry_2' '_geom_angle_site_symmetry_3'

Category: geom_angle

Data type: char

Must appear in a looped list containing '_geom_angle_atom_site_label_'


. 'no symmetry or translation to site'
4 '4th symmetry operation applied'
7_645 '7th symm. posn.; +a on x; -b on y'


The symmetry code of each atom site as the symmetry-equivalent position number 'n' and the cell translation number 'klm'. These numbers are combined to form the code 'n klm' or n_klm. The character string n_klm is composed as follows: n refers to the symmetry operation that is applied to the coordinates stored in _atom_site_fract_x, _atom_site_fract_y and _atom_site_fract_z. It must match a number given in _symmetry_equiv_pos_site_id. k, l and m refer to the translations that are subsequently applied to the symmetry transformed coordinates to generate the atom used in calculating the angle. These translations (x,y,z) are related to (k,l,m) by the relations k = 5 + x l = 5 + y m = 5 + z By adding 5 to the translations, the use of negative numbers is avoided.

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