STRUCTURAL COMPLEXITY OF MOLECULAR, CHAIN, AND LAYERED CRYSTAL STRUCTURES OF NATURAL AND SYNTHETIC ARSENIC SULFIDES

Abstract

A ladder-wise calculation scheme has been developed for the structural complexity of heterodesmic crystal structures, with crystal interpreted as a system of contacting molecules, chains, and layers. In the last stage of ladder-wise calculation the structural complexity of the main motif is summed with the complexity of the contacts beyond the main motif in correspondence with the strong additivity rule. The application potential of the scheme is demonstrated, and the calculation results for the crystal structures of natural and synthetic arsenic sulfides are presented. The coordination of molecules and chains that is necessary for calculating the complexity of contacts beyond the main motif is determined by the method of Voronoi–Dirichlet polyhedra.