Effect of Solute-Solvent Interaction on the Molecular Association in a Hard Sphere Fluid

Abstract

Effect of solute-solvent interaction on the solute-solute distribution function is studied for a system in which the solute molecules are dissolved in a hard-sphere fluid at infinite dilution. The solute-solvent interaction is a square-well potential and the solvent molecule in the well is assumed to have a bond with the solute molecule. An ideal-gas approximation reveals that a solute-solvent attractive interaction, as well as a repulsive interaction, can stabilize the solute pair through the fluctuation of the bond number. The Monte Carlo calculations showed that the ideal-gas approximation becomes invalid with increasing density. Solvent-solvent correlation at high densities brings about a complicated fluid structure around a solute pair and reduces the fluctuation of the bond-number.