Solute-Enhanced Diffusion in a Dense Two-Dimensional Liquid

Self-diffusion in dense two-dimensional liquids consisting of mixtures of soft disks is studied using constant-temperature--constant-pressure molecular dynamics simulations. At low solute concentrations, both the solute and solvent diffusion constants are found to exhibit a nonmonotonic dependence on the solute diameter. The anomalously high diffusion of the solute is shown to arise from the disruption of the local solvent structure and the resulting increase in the solvent mobility.