Studies in molecular dynamics. XV. High temperature description of the transport coefficients

Abstract

The power series expansion of the transport coefficients in the attractive potential relative to the kinetic energy does not exist. However, the first term in this expansion appears to exist and is evaluated indirectly by molecular dynamics at various densities. For the diffusion coefficient this first term is predicted quantitatively at high density by the enhanced local density in the region of the attractive potential relative to that of the hard sphere system. Furthermore, since the enhanced density does not affect the kinetic contribution to the viscosity and thermal conductivity, these transport coefficients compare favorably with the predictions of the Boltzmann equation. An explicit calculation of the first term requires statistical mechanical averaging before expansion, a procedure unsuitable to molecular dynamics computations and which has as yet been unattained analytically at any finite density.