System-specific discrete variable representations for path integral calculations with quasi-adiabatic propagators

Discrete variable representations (DVRs), constructed numerically from eigenstates of the one-dimensional adiabatic potential, provide the optimal quadrature for evaluating quasi-adiabatic propagator path integrals (QUAPI) for a system coupled to a harmonic bath. Calculations of partition functions and reaction rates for a multiple-minimum potential in a dissipative environment illustrate the convergence characteristics of this approach. The small number of quadrature points required, along with the rapid convergence of QUAPI methods, results in a powerful numerical scheme, complementary to Monte Carlo methods, for performing condensed phase dynamics calculations over the entire temperature range of interest in chemical physics.