Thermal conductivity of the Lennard-Jones liquid by molecular dynamics calculations

Abstract

Precise results for the thermal conductivity of the Lennard-Jones liquid obtained by equilibrium molecular dynamics (MD) are presented. These are compared in detail with previous nonequilibrium MD results. Effects due to the truncation of the potential and the particle number dependence are considered. The contributions of the partial correlation functions to the total one were separately calculated. Main results are: (i) in contrast to the viscosity, the thermal conductivity is rather insensitive to the MD conditions, even for the state corresponding virtually to the triple point of argon. The reason for this originates from the simple short ranged time decay of the correlation function. (ii) For the states considered, the partial correlation function involving the ‘‘potential–potential’’ term governs the transport coefficient. (iii) Nonequilibrium MD and MD give consistent values, except for the nonequilibrium method devised by Heyes which generates data far off the range permitted by the error bars. (iv) The computed thermal conductivities fall well in line with experimental data for argon.