Investigation of structure and stability of small clusters: Molecular dynamics studies of water pentamers

The method of molecular dynamics was used to examine the structure and stability of water pentamers for a variety of initial configurations. The evolution of each configuration was followed over a temperature range of 5 to ∼300 K. It was found that at low temperatures, insufficient energy was present for structure interconversion. Thus a time average was not equivalent to a phase space average and the pentamer cluster system is not ergodic below ∼60 K. In addition to the structure studies, collisions of a water monomer with the pentamer cluster were modeled using different impact parameters. In the collisions, only small energy transfer was required for monomer absorption. Re-evaporation or evaporation events in either the collision simulations or the heating runs were rare.