Molecular dynamics study and parametrisation of the infinite-frequency shear and compressional moduli of the Lennard-Jones fluid

Abstract

The infinite-frequency shear modulus, G_∞, and compressional modulus, K_∞, of the Lennard-Jones, LJ, fluid have been determined over essentially the whole phase diagram at densities below the solid–fluid coexistence line for each temperature. It is shown that the mechanical properties of the LJ fluid are the same as those of the hard-sphere fluid on assignment of a separately derived effective hard-sphere diameter. The shear modulus is marginally better at scaling than the compressional modulus, in keeping with previous observations for the LJ shear and bulk viscosity. The simulation LJ moduli can be reproduced from new, simple expressions which are similar to those observed experimentally for colloidal suspensions.