Global potential energy surfaces of water clusters; Reaction coordinate and annealing analyses

A global nature of the potential energy surface (PES) of water clusters, (H2O)(20) and (H2O)(54) was investigated by using a reaction coordinate analysis and an annealing method. It was shown for (H2O)(64) that the successive reaction coordinates passing through low energy barriers lead to a deep minimum and the overall potential has so called a funnel structure, similar to PES of a protein folding. On the other hand, the smaller cluster (H2O)(20) has the rugged PES of a 'fragile' type, resulting from distinct bond reordering. (C) 1998 Elsevier Science B.V.