Integral equation and Monte Carlo simulation studies of clusters in infinitely dilute supercritical solutions

We present a systematic study of both the size and attractive interaction strength effects on solvent clustering in infinitely dilute supercritical solutions. Both integral equation and computer simulation methods are brought to bear. We argue that monitoring the net local solvent density change due to the presence of the solute as well as residual solute chemical potential offers a predictive way of identifying clustering or declustering in infinitely dilute supercritical solutions. Phase diagram-like figures can be obtained, wherein the ‘phase boundaries’ divide the solvent enrichment (or effective attraction) from the solvent depletion (or effective repulsion) region. In conjunction with the corresponding states analyses these diagrams can provide a useful semiquantitative means of predicting the nature of solvation in many supercritical fluid systems.