Much of our research during the last ten years has focussed on the dynamics of elementary chemical reactions in the gas phase. We have learned a great deal during this time about the interpretation of transition state spectroscopy experiments, the role of quantum mechanical resonances in hydrogen atom transfer reactions, the significance of the electronically non-adiabatic effects caused by electronic and spin-orbit couplings, the effect of van der Waals forces on chemical reaction dynamics, and the statistical nature of insertion reactions that proceed via deep potential energy wells.
We have recently shown how the standard path integral molecular dynamics (PIMD) method, which has been used for the last twenty years to calculate the exact static equilibrium properties of quantum mechanical systems, can be generalized to calculate approximate real-time quantum correlation functions, and so used to study the role of quantum effects in condensed phase molecular dynamics. The resulting ring polymer molecular dynamics (RPMD) method has already been applied to a model for proton transfer in solution and to the quantum diffusion in liquid para-hydrogen, with encouraging results in both cases. We are now planning to use the method to study a wider variety of dynamical processes in both strongly quantum fluids like liquid hydrogen and mildly quantum fluids like liquid water.