Self-diffusion of a relativistic Lennard-Jones gas via semirelativistic molecular dynamics.

The capability for molecular dynamics simulations to treat relativistic dynamics is extended by the inclusion of relativistic kinetic energy. In particular, relativistic corrections to the diffusion coefficient are considered for an argon gas modeled with a Lennard-Jones interaction. Forces are transmitted instantaneously without being retarded, an approximation that is allowed due to the short-range nature of the Lennard-Jones interaction. At a mass density of 1.4g/cm^{3}, significant deviations from classical results are observed at temperatures above k_{B}T≈0.05mc^{2}, corresponding to an average thermal velocity of 32% of the speed of light. For temperatures approaching k_{B}T≈mc^{2}, the semirelativistic simulations agree with analytical results for hard spheres, which is seen to be a good approximation as far as diffusion effects are concerned.