Diffusion in the hard sphere fluid

Abstract Values of the self diffusion coefficient D HS in the hard sphere fluid, which have been measured by computer simulation are re-assessed. The resulting values are precisely represented by where n = ρσ3, ρ = N/V is the number density and σ is the sphere diameter. D 0 = ⅜σ(k B T/πm 1/2 where k B T is Boltzmann's constant times the temperature and m is the mass of a sphere. The equation is accurate over the whole density range from the ideal gas limit, where it is exact, to the highest density ρσ3 = 1·08 at which the metastable fluid has been studied. The equation is consistent with the idea that the hard sphere fluid has a singularity at ρσ3 = 1·09 at which diffusion ceases.