Open System Approach to the Internal Dynamics of a Model Multilevel Molecule

Abstract

A model multilevel molecule described by two sets of rotational internal energy levels of different parity and degenerate ground states, coupled by a constant interaction, is considered, by assuming that the random collisions in a gas of identical molecules, provoke transitions between adjacent energy levels of the same parity. The prescriptions of the continuous time quantum random walk is applied to the single molecule, interpreted as an open quantum system, and the master equation driving its internal dynamics is built for a general distribution of random collision times. Over estimated long time scales, the dynamics of the coherence terms and the populations of the energy levels is evaluated analytically for relevant classes of non-Poissonian distributions of the collision times. Inverse power law relaxations and the inverse Zeno effect emerge over estimated long time scales and the stable asymptotic equilibrium configuration results to be independent of the distribution of the collision times.