Semiclassical influence functionals for quantum systems in anharmonic environments

A rigorous semiclassical methodology for calculating influence functionals arising from polyatomic anharmonic environments is presented. Integration of each trajectory forward and backward in time reduces the severity of the oscillations in the semiclassical propagator, namely those originating from the dynamics of the isolated environment, and leads to a convenient coherent state initial value representation which is amenable to Monte Carlo sampling. The advantages of this formulation are illustrated through an example employing a harmonic oscillator bath.