Transport properties of molecular liquids

Abstract

Dynamic processes in atomic liquids are nowadays very well understood in terms of kinetic theory and computer calculations. Transport coefficients and dynamic scattering functions of the example liquid argon are well reflected by kinetic theories and molecular dynamics calculations using the Lennard-Jones (LJ) pair potential. The present review gives a summarizing account of these results. The situation for molecular liquids like carbon dioxide, benzene or cyclohexane, is not so satisfactory. Kinetic theories are practically lacking for these fluids, and molecular dynamics computations exist only in much lower number. Nonetheless, during the last five years our understanding of the dynamics in molecular liquids has been greatly improved by equilibrium and nonequilibrium molecular dynamics calculations. Our review presents this progress in terms of results for thermal transport coefficients, one particle and collective dynamic properties as well as time correlation functions. An extensive comparison of computed and measured transport properties is additionally given. Finally, an attempt is made to discuss the Soret effect in molecular fluids, although the research on this topic is not yet completed.