title: The model of level broadening in condensed phase.
abstract: We study a model of non-Markovian kinetics for a harmonic oscillator embedded in a harmonic heat bath. We present a new scheme for approximately solving the quantum relaxation equation for the density matrix to find a distribution of level populations. It is found to be an extended Lorentzian with the width depending on the energy. A more convenient non-Markovian distribution called square root Fourier distribution that was implemented in the preceding paper [M. V. Basilevsky et al., J. Chem. Phys. 125, 194513 (2006)] is closely related to this extended Lorentzian model. Both distributions decay exponentially far away from their centers and reproduce well standard Lorentzian widths in the vicinity of the central region. A conventional Lorentzian model with such widths results when the Redfield approximation is applied in the frame of the present procedure.
authors.affiliation: Photochemistry Center, Russian Academy of Science, ul. Novatorov 7a, Moscow 117421, Russia. basil@photonics.ru
authors.forename: M V
authors.initials: MV
authors.lastname: Basilevsky
authors.forename: G V
authors.initials: GV
authors.lastname: Davidovich
authors.forename: A I
authors.initials: AI
authors.lastname: Voronin