THE SOLVATION REACTION FIELD FOR A HYDROGEN-ATOM IN A DIELECTRIC CONTINUUM

A reaction field exists even for a nonpolar solute embedded in a spher ical cavity within a surrounding homogeneous dielectric continuum. Thi s arises from the tail of the electronic wave function that penetrates beyond the cavity boundary into the dielectric region. This effect, w hich is neglected or treated only in cursory fashion in most reaction field implementations, is examined in detail for the simple case of a ground state hydrogen atom, where very accurate solutions of the relev ant equations can be obtained. Properties considered include the penet ration of the electron outside the cavity, the electronic density at t he nucleus, the electron binding energy, the electrostatic free energy of solvation, the polarizability, and the vertical 1s --> 2p excitati on energy. Also, the effect of the common approximation of neglecting the volume polarization and treating only the surface polarization con tribution to the reaction field is critically evaluated. (C) 1996 Amer ican Institute of Physics.