Self-diffusion coefficients of Lennard-Jones fluids

Expressions for the selfdiffusion coefficient have been obtained using the memory function formalism and the frequency moments of the velocity autocorrelation function. The fourth and the sixth frequency moments of the velocity autocorrelation function have been calculated using a low-order decoupling and the superposition approximation for the static quadruplet and the triplet correlation functions, respectively. These results have been used to calculate the diffusion coefficients of Lennard-Jones fluids over a wide range of densities and temperatures. The predicted results are found to be in good agreement with recent molecular dynamics data.