Molecular Dynamics Study of Solute-Solute Microstructure in Attractive and Repulsive Supercritical Mixtures

Molecular dynamics simulations show enhancements in the density of solute molecules around each other in model attractive and repulsive dilute supercritical Lennard-Jones mixtures. The effect is pronounced in the former case and moderate in the latter. For the attractive mixture, the quantification of the density enhancement in terms of excess number of solute molecules suggests an increased collision frequency rather than the formation of a compact solute-solute aggregate. The simulations confirm the results of recent integral equation calculations for the same model mixtures, and suggest that solute-solute interactions in dilute supercritical mixtures could play an important role in situations involving a reactive solute.