Computing Ion Solvation Free Energies Using the Dipolar Poisson Model

A new continuum model is presented for computing the solvation free energies of cations in water. It combines in a single formalism based on statistical thermodynamics the Poisson model for electrostatics with the Langevin dipole model to account for nonuniform water dipole distribution around the ions. An excellent match between experimental and computed solvation free energies is obtained for 10 monovalent and divalent ions.