Crystallography Reports, Vol. 42, No. 5, 1997, pp. 707 713. Translated from Kristallografiya, Vol. 42, No. 5, 1997, pp. 773 779.
Original Russian Text Copyright 1997 by Blatov, Shevchenko, Serezhkin.
Occurrence Frequency of Space Groups. Topological Aspect of the Problem. II. Orthorhombic System
V. A. Blatov, A. P. Shevchenko, and V. N. Serezhkin
Samara State University, Samara, Russia
Received December 5, 1995; in final form, January 9, 1997
Abstract Specific topological features of the Voronoi Dirichlet division of the crystal space M3 , in which the symmetry of the regular point system is given by one of the space groups of the orthorhombic system, have been studied. The criteria of the occurrence frequency of space groups suggested earlier are refined. A rule is formulated according to which the topology of the space M3 would not hinder packing of soft or hard structural groupings. The principle of close packing of structural units suggested by Kitaigorodsky is complemented with the principle of loose covering. The advantages of the suggested structure model of a crystal as a packing of deformable spheres are considered for some examples.