Stochastic classical trajectory approach to relaxation phenomena. III. Comparison of trajectory results to quantum mechanical perturbation theory

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Abstract
A simple model representing an impurity oscillator coupled anharmonically to a lattice is examined both by quantum mechanical perturbation theory and by stochastic classical trajectory simulations. Energy relaxation rates are computed as a function of temperature. Classical and quantum relaxation rates are found to agree well at high temperatures but, as expected, diverge drastically at low temperatures. If zero‐point motion of the lattice is incorporated into the classical calculation, classical and quantum relaxation rates agree quite well for all temperatures, even for T→0. This suggests that the stochastic classical trajectory method can provide an accurate description of relaxation phenomena even at very low temperatures.