Journal of Chemical Physics, Vol.101, No.5, 3750-3762, 1994
Rearrangements of 55-Atom Lennard-Jones and (C-60)(55) Clusters
Roughly 3000 rearrangement pathways have been calculated for each of two clusters bound by simple empirical potentials. The first system is the 55-atom complex described by a pairwise Lennard-Jones potential. The second consists of 55 C-60 molecules with an intermolecular potential obtained by spherically averaging atom-atom Lennard-Jones terms, as previously employed in bulk simulations. Various properties of the pathways are calculated, such as a cooperativity index and the integrated path length, and the probability distributions are subjected to statistical analysis. Systematic differences between the atomic Lennard-Jones 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 convergence of the eigenvector-following method employed to optimize the geometries and follow the pathways.
Keywords:POTENTIAL-ENERGY SURFACES;QUADRATIC STEEPEST DESCENT;TRANSITION-STATES;STATIONARY-POINTS;SADDLE-POINTS;GEOMETRY OPTIMIZATION;MOLECULAR-DYNAMICS;ARGON CLUSTERS;WATER DYNAMICS;REACTION PATHS