Unbiased Geometry Optimisation of Morse Atomic Clusters

Abstract

This paper presents the results obtained using an unbiased Population Based Search (PBS) for optimising Morse atomic clusters. PBS is able to repeatedly obtain all putative global minima for Morse clusters in the range 5 = N = 80, N = 147, ? = 3,6,10, 14, as reported in the Cambridge Cluster Database. In addition, putative global minima have been established for Morse clusters in the range 81 = N = 146, ? = 14. The PBS algorithm incorporates and extends key techniques that have been developed in other cluster optimisation algorithms over the last decade. Of particular importance are the use of cut and paste operators, structure niching and a new operator, Directed Optimisation, which extends the previous concept of directed mutation. In addition, PBS is able to operate in a parallel mode for optimising larger clusters.