THE OPTIMIZED ELLIPSOIDAL CAVITY AND ITS APPLICATION TO THE SELF-CONSISTENT REACTION FIELD CALCULATION OF HYDRATION ENERGIES OF CATIONS AND NEUTRAL MOLECULES

An optimized ellipsoidal cavity has been defined for use in self-consistent reaction field (SCRF) calculations for the incorporation of aqueous medium effects. The location, size, and orientation of the cavity is obtained by minimizing the average interaction between the solute and a simplified water molecule over the surface of the cavity. The calculated hydration energies of organic cations and neutral molecules using this cavity and the SCRF method of Rinaldi and Rivail with the AM1 wave function led to suprisingly good agreement with the experimental data. The optimized cavities are discussed in relation to those based on van der Waals' volumes and on polarizability criteria.