A test of the modified Enskog theory for self-diffusion

Abstract

The method of molecular dynamics has been used to calculate the self-diffusion coefficient for a system of particles whose pairwise additive interactions are governed by the Lennard-Jones/spline potential, a finite ranged modification of the Lennard-Jones potential. The coefficient of self-diffusion D has been calculated for the states nσ3 = 0·05, 0·1, 0·2, 0·3, 0·4, and 0·5, with k B T/e = 2·0 (n is the number density, T the temperature, k B Boltzmann's constant, and σ and e are the length and energy parameters of the Lennard-Jones potential). The non-equilibrium molecular dynamics calculations were made for systems having N particles, with N = 256, 500, and 1372. D was obtained by extrapolating the finite N results to the N = ∞ limit. To evaluate the modified Enskog theory (MET) we calculated the second and third virial coefficients and D 0, the dilute gas value of D, by numerical quadrature. The thermal pressure T(δp/δT) n , which plays a central role in the MET, was calculated using molecular dynamics...