Mass dependence of the self diffusion in a liquid

The influence of the particle mass on the self diffusion is determined from an analysis of the time behaviour of a single, heavy isotope. The time behaviour is obtained from molecular dynamics calculations for a Lennard-Jones liquid. The analysis of the Mori coefficients, the velocity autocorrelation and the self diffusion confirms the weak mass dependence of the diffusion constant previously obtained, and demonstrates that this is because the gaussian memory dominates for large isotope masses.