Topological analysis of ionic packings in crystal structures of inorganic sulfides: the method of coordination sequences

Using the concept of coordination sequences and the uniformity criterion th e method of topological analysis of atomic packings and of their classifica tion at any degree of metric distortions is implemented in the computer pro gram IsoTest. The criterion is based on the search for packings topological ly similar, but not equal to close packings. The topological analysis of io nic sublattices was employed for the crystal structures of 781 inorganic su lfides. It was shown that no less than in the third of cases the sulfides a re constructed on the basis of a distorted close packing, and such packings are constructed with sufficiently large cations, as a rule. The examples o f forming close packings by complex thioanions contained in a number of thi osalts were drawn.