An SCF Solvation Model for the Hydrophobic Effect and Absolute Free Energies of Aqueous Solvation

A model for absolute free energies of solvation of organic, small inorganic, and biological molecules in aqueous solution is described. This model has the following features: (i) the solute charge distribution is described by distributed monopoles, and solute screening of dielectric polarization is treated with no restrictions on solute shape; (ii) the energetic effects of cavity formation, dispersion interactions, and solute-induced restructuring of water are included by a semiempirical cavity surface tension; and (iii) both of these effects are included in the solute Hamiltonian operator for self-consistent field (SCF) calculations to allow solvent-induced electronic and geometric distortion of the solute. The model is parameterized for solutes composed of H, C, N, O, F, P, S, Cl, Br, and I against experimental data for 150 neutral solutes and 28 ions, with mean absolute errors of 0.7 and 2.6 kilocalories per mole, respectively.