REARRANGEMENTS OF 55-ATOM LENNARD-JONES AND (C-60)(55) CLUSTERS

Roughly 3000 rearrangement pathways have been calculated for each of t wo clusters bound by simple empirical potentials. The first system is the 55-atom complex described by a pairwise Lennard-Jones potential. T he second consists of 55 C-60 molecules with an intermolecular potenti al obtained by spherically averaging atom-atom Lennard-Jones terms, as previously employed in bulk simulations. Various properties of the pa thways are calculated, such as a cooperativity index and the integrate d path length, and the probability distributions are subjected to stat istical analysis. Systematic differences between the atomic Lennard-Jo nes clusters and the C-60 molecular clusters are explained in terms of the effective pair potential; e.g., rearrangements of (C-60)(5)5 are generally localized because the potential is relatively short ranged. A pseudo-third-derivative correction is developed to improve the conve rgence of the eigenvector-following method employed to optimize the ge ometries and follow the pathways.