### Gas phase dynamics

Much of our research in the last twenty years has focused on the quantum mechanical description 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 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.

### Condensed phase dynamics

We have recently shown how the standard path integral molecular dynamics (PIMD) method, which has been used since the mid 1980s to compute 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 mechanical (zero point energy and tunnelling) effects in condensed phase chemical dynamics. The resulting ring-polymer molecular dynamics (RPMD) model has already been used to study the diffusion in and the inelastic neutron scattering from liquid para-hydrogen, various dynamical processes in ice and water, and chemical reaction rates in the gas phase and in solution. We are now continuing to use PIMD and RPMD to study a wide variety of structural, thermodynamic, and dynamical properties of condensed phase systems containing hydrogen atoms.

Asymmetric recombination and electron spin relaxation in the semiclassical theory of radical pair reactions. A. M. Lewis, D. E. Manolopoulos and P. J. Hore, J. Chem. Phys. 141, 044111 (2014).

Ring polymer molecular dynamics: Quantum effects in chemical dynamics from classical trajectories in an extended phase space. S. Habershon, D. E. Manolopoulos, T. E. Markland and T. F. Miller, Ann. Rev. Phys. Chem. 64, 387-413 (2013).

The inefficiency of re-weighted sampling and the curse of system size in high-order path integration. M. Ceriotti, G. A. R. Brain, O. Riordan and D. E. Manolopoulos, Proc. Roy. Soc. A 468, 2 (2012).

Bimolecular reaction rates from ring polymer molecular dynamics: Application to H+CH4 to H2+CH3. Y. V. Suleimanov, R. Collepardo-Guevara and D. E. Manolopoulos, J. Chem. Phys. 134, 044131 (2011).

Efficient stochastic thermostatting of path integral molecular dynamics. M. Ceriotti, M. Parrinello, T. E. Markland and D. E. Manolopoulos, J. Chem. Phys. 133, 124104 (2010).

Competing quantum effects in the dynamics of a flexible water model. S. Habershon, T. E. Markland and D. E. Manolopoulos, J. Chem. Phys. 131, 024501 (2009).