Recursive evaluation of the real-time path integral for dissipative systems. The spin-boson model

The tunneling dynamics of an electronic two-state system coupled to a bath of harmonic oscillators at zero temperature is treated using a real-time path-integral approach. In the present work the previously developed recursive class-average approach is extended to include the Feynman-Vernon influence functional and to evaluate electronic population probabilities. The efficiency and accuracy of the method is demonstrated by application to two model problems taken from recent literature.