Fig. 4. Comparison with the molecular dynamics simulations of the hard-sphere fluid.

a–c Self-diffusion coefficient D from our measurements of methane (full circles) and from the simulation results for the hard-sphere fluid reported in ref. ⁴⁸ (lines), as a function of density. Simulated values are reported for: a A = 1.00 and six different values of the hard-sphere diameter σ, b σ = 3.5 Å and five different values of the translation-rotation coupling parameter A, and c A = 0.67 and σ = 3.39 Å, A = 0.927 and σ from the fit of d. d σ values for which Eq. (3) is satisfied with A = 0.927, as a function of density, and the best sigmoidal fit (dashed line). Error bars correspond to one standard deviation.