Graph theoretical enumeration of topology-distinct structures for hydrogen fluoride clusters (HF)n (n ≤ 6).

Abstract

A graph theoretical procedure to generate all the possible topology-distinct structures for hydrogen fluoride (HF) clusters is presented in this work. The hydrogen bond matrix is defined and used to enumerate the topology-distinct structures of hydrogen fluoride (HF)n (n = 2-8) clusters. From close investigation of the structural patterns obtained, several restrictions that should be satisfied for a structure of the HF clusters to be stable are found. The corresponding digraphs of generated hydrogen bond matrices are used as the theoretical framework to obtain all the topology-distinct local minima for (HF)n (n ≤ 6), at the level of MP2/6-31G**(d, p) of ab initio MO method and B3LYP/6-31G**(d, p) of density functional theory method. For HF clusters up to tetramers, the local minimum structures that we generated are same as those in the literature. For HF pentamers and hexamers, we found some new local minima structures which had not been obtained previously.