Bulk viscosity of the Lennard-Jones fluid for a wide range of states computed by equilibrium molecular dynamics

Abstract

Accurate data for the bulk viscosity η_v have been obtained by molecular dynamics calculations. Many thermodynamic states of the Lennard‐Jones fluid were considered. The Green–Kubo integrand of η_v is analyzed in terms of partial correlation functions constituting the total one. These partial functions behave rather differently from those found for the shear viscosity or the thermal conductivity. Generally the total autocorrelation function of η_v shows a steeper initial decay and a more pronounced long time form than those of the shear viscosity or the thermal conductivity. For states near transition to solid phases, like the pseudotriple point of argon, the Green‐Kubo integrand of η_v has a significantly longer ranged time behavior than that of the shear viscosity. Hence, for the latter states, a systematic error is expected for η_v using equilibrium molecular dynamics for its computation.