A mode-coupling approach to the attractive interaction effect on the solute diffusion in liquids

摘要

The effect of the solute-solvent and the solvent-solvent attractive interactions on the diffusion coefficient of the solute is studied by the mode"'eoupling theory .The mode-coupling part of tIle friction coefficient in our calculation is compared with that of molecular dynamics simulation. The theory qualitatively reproduces the increase in the friction coeffic~ent with the solute-solvent attractive interaction, although the absolute value is larger than the simulation. A theoretical scheme is further provided to divide the memory function into attractive and repulsive components, and a mode-coupling approximation is introduced to both components separately. It is found that the solute-solvent interaction affects the attractive friction mainly, in agreement with the simulation. Further analyses reveal the presence of the large cross term of the attractive and repulsive random forces. When the solvent-solvent attractive interaction is weakened while keeping the solute- solvent interaction fixed, the mode-coupling friction is increased, which is opposite to the simulation results.