Path Integral Energy Landscapes for Water Clusters.

Abstract

The energy landscape for a discretised path integral representation of the water dimer is characterized in terms of the localised (classical) and delocalised minima and transition states. The transition states are finite-temperature approximations to the exact instanton path, and are typically used to calculate the tunneling splittings or reaction rates. The features of the path integral landscape are explored, thus elucidating procedures that could usefully be automated when searching for instantons in larger systems. Our work not only clarifies the role of minima and transition states in path integral calculations, but also enables us to analyse the quantum-to-classical transition.