OCCURRENCE FREQUENCY OF SPACE-GROUPS - TOPOLOGICAL ASPECT OF THE PROBLEM .2. ORTHORHOMBIC SYSTEM

Specific topological features of the Voronoi-Dirichlet division of the crystal space M-3, in which the symmetry of the regular point system is given by one of the space groups of the orthorhombic system, have b een 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 M-3 would not hinder packing of soft or har d structural groupings. The principle of close packing of structural u nits suggested by Kitaigorodsky is complemented with the principle of loose covering. The advantages of the suggested structure model of a c rystal as a packing of deformable spheres are considered for some exam ples.