The Enskog theory for classical vibrational energy relaxation in fluids with continuous potentials

Abstract

The recently developed Enskog theory for binary friction for fluids with continuous potentials, such as the Lennard-Jones, has been extended to calculate the frequency dependence of this friction, ζ_E(ω). This ζ_E(ω) is then applied to study vibrational energy relaxation of low-frequency modes via the Landau-Teller expression. The agreement with simulation results is found to be satisfactory. In the present approach we provide an exact prescription for the binary friction and thus remove a lacuna in this area. ζ_E(ω) shows an interesting structure with a hump at low frequency, the signature of which has already been seen in many simulation studies.