Energy current density correlation function. II. Thermal conductivity

Abstract

Expressions for the energy current density correlation function and the thermal conductivity have been derived using a continued-fraction representation of correlation function. A secant hyperbolic, a Gaussian and an exponential form of the memory function have been used. The parameters appearing in the memory function are determined from the zeroth-, second- and fourth-frequency sum rules of the energy current density correlation function. For the time dependence of the energy current density correlation function and the thermal conductivity, the results obtained for the Lennard-Jones fluids, have been compared with recent computer simulation data. Overall good agreement has been obtained over a wide range of densities and a wide range of temperatures.