POLARIZED ONE-ELECTRON POTENTIALS FITTED BY MULTICENTER POLARIZABILITIES AND HYPERPOLARIZABILITIES - AB-INITIO SCF-CI CALCULATION OF WATER

The electrostatic potential is usually evaluated by putting a test charge at several points on an appropriate molecular surface. The polarization effect is an indispensable long-range interaction as well as the electrostatic interaction. To evaluate the polarization effect, it is necessary to relax the wavefunction under the perturbed Hamiltonian. In the present work the polarized molecular potentials based on the ab initio SCF-CI method have been fitted by multicenter polarizabilities and hyperpolarizabilities. The polarization energies and induced dipole moments calculated by using the fitted parameters have been significantly improved by including the first hyperpolarizabilities in the case of a water molecule.