Accurate first principles calculation of molecular charge distributions and solvation energies from ab initio quantum mechanics and continuum dielectric theory

A combination of high-level ab initio quantum mechanics and continuum dielectric theory helps evaluate the solvation free energies of organic solutes in water. Gas-phase charge distributions are obtained by employing correlated wave functions at the valence bond/perfect pairing level. These charge distributions help derive the solvation energies. Application of this method for 29 molecules produces an average error of 0.6 kcal/mol for solvation energies, however theoretical predictions significantly differ from experimental observation of solvation energies for methylated and unmethylated primary amines and amides.