EXCITED-STATES AND SOLVATOCHROMIC SHIFTS WITHIN A NONEQUILIBRIUM SOLVATION APPROACH - A NEW FORMULATION OF THE INTEGRAL-EQUATION FORMALISM METHOD AT THE SELF-CONSISTENT-FIELD, CONFIGURATION-INTERACTION, AND MULTICONFIGURATION SELF-CONSISTENT-FIELD LEVEL

The effects of the solvation on excited states are studied in the fram ework of a nonequilibrium regime between solute and solvent charge dis tributions. The approach, which exploits a separation of the polarizat ion into slow and fast components, is inserted in a new formulation of the recently developed continuum solvation model known as integral eq uation formalism. This new version, implying a large computational gai n both in time consuming and memory occupation, is here implemented at the Hartree-Fock level as well as at the multiconfiguration self-cons istent field and configuration interaction levels. Examples of applica tion of the method to solvatochromic shifts for low-lying excitation e nergies of formaldehyde, acetaldehyde, and acetone in water are shown. (C) 1998 American Institute of Physics.