Quantum oscillator in a heat bath

Abstract

In the present article, we use the density matrix evolution method to study the effect of a model solvent on the vibrational spectrum of a diatomic solute particle. The effect of the solvent is considered as a perturbation on the Hamiltonian of the quantum subsystem consisting of a harmonic oscillator. The bath particles are treated classically. The perturbation potential representing the interaction between the solute and the solvent is represented in a bi-exponential form. This provides an effective way to evaluate the required matrix elements needed to compute the evolution of the density matrix. The model calculations indicate that the repulsive parts of the potential dominate causing blue shifts in the vibrational frequencies. © 2009 Springer Berlin Heidelberg.