Toward Accurate Solvation Free Energy Calculation with the Reference Interaction Site Model Self-Consistent Field: Introduction of a New Bridge Function.

The reference interaction site model self-consistent field (RISM-SCF) has the potential to become a powerful tool for studying solution chemistry because of its low computational cost and the capability of calculating local solvation structures accurately, such as hydrogen bonding. However, RISM-SCF has a critical weakness: it is not possible to accurately reproduce the experimental data for solvation free energy. In this study, we proposed a new bridge function and combined it with the repulsive bridge correction (RBC) proposed by Kovalenko and Hirata. To verify the effectiveness of our approach, we computed the hydration free energies of 70 organic molecules. Our method successfully improved the overestimation of the cavitation free energy inherent in the original RISM-SCF.