This is an archive copy of the IUCr web site dating from 2008. For current content please visit https://www.iucr.org.

Modulated Structures CIF Dictionary version 1.0

_atom_sites_modulation_global_phase_t_

Names

'_atom_sites_modulation_global_phase_t_1' '_atom_sites_modulation_global_phase_t_2' '_atom_sites_modulation_global_phase_t_3' '_atom_sites_modulation_global_phase_t_4' '_atom_sites_modulation_global_phase_t_5' '_atom_sites_modulation_global_phase_t_6' '_atom_sites_modulation_global_phase_t_7' '_atom_sites_modulation_global_phase_t_8'

Category: atom_sites_modulation

Data type: numb _enumeration -1.0:1.0
Enumeration default: 0.0

Units: cy ( Cycles)

Definition

    	
   The initial phases in cycles of the modulation waves. For
   incommensurate structures they are irrelevant. However they are
   essential for the description of commensurate structures within
   the superspace formalism since they determine the space group
   of the commensurate superstructure [see Perez-Mato, J.M.,
   Madariaga, G., Zu\~niga, F. J. & Garcia Arribas, A. (1987),
   Acta Cryst. A43, 216-226 or van Smaalen, S. (1995),
   Cryst. Rev. 4, 79-202]. Notice that for composites described
   using a single data block the initial phases for each subsystem
   are derived using the W matrices (see _cell_subsystem_matrix_W_)
   from a unique set of global phases whose values are assigned to
   _atom_sites_modulation_global_phase_t_. Detailed information can
   be found in the above cited reference of van Smaalen.

IUCr Webmaster