AN APPLICATION OF THE REACTION FIELD-THEORY TO HYDRATED METAL-CATIONSIN THE FRAMEWORK OF THE MNDO, AM1, AND PM3 METHODS

A reaction field theory, combined with the MNDO, AM1, and PM3 molecula r orbital methods, was applied to hydration phenomena of metal cationi c species. The first hydration shell was treated explicitly by using a supermolecular model, [M(H2O)(n)](m+), and its surrounding medium was described with a continuum dielectric. Hydration free energies were e valuated as a sum of the contributions from the electrostatic interact ion with the bulk medium, the hydrated cluster formation, the cavity f ormation, and the vaporization of water molecules forming the cluster. As a whole, calculated hydration energies were in good agreement with the corresponding experimental data over various kinds of metal catio nic species. (C) 1995 by John Wiley & Sons, Inc.