A method for topological analysis of rod packings

A method for analysis of geometrical and topological properties of crystal structures, which contain one-periodic (chain-like) structural units, is proposed and implemented as a computer procedure into the program package ToposPro. The method is based on representation of the set of parallel chains as two kinds of two-periodic nets: rod net, which characterizes the way of linking the chains with each other, and rod packing net, which describes the method of spatial arrangement of the chains irrespective of their interconnections. The geometrical (Domains method) and topological criteria are formulated to construct rod nets and rod packing nets from the initial crystallographic data. It is shown that rod packing net formalizes earlier classifications of rod packings in crystals. Examples are presented, which demonstrate the applications of the method to one-periodic coordination polymers, metal-organic frameworks, and hydrogen-bonded molecular crystals.