A new method is formulated for evaluating solvent effects on the absorption maxima of molecules. The method is based on a self-consistent reaction field polarizable continuum model (SCRF-PCM), coupled with the configuration Interaction (CI) procedure. We proposea new scheme in which the polarization of solvent, induced by the excitation of a solute molecule, is partitioned into orientational and electronic contributions, and the exact expression of excitation energy is derived with nonspecific parameters of solvents, i.e., dielectric constant and refractive index. On the basis of this result, the expression of the diagonal element of the CI matrix is derived. In addition, we show that the expression of the off-diagonal element can be obtained without losing generality under the condition that the solute wave, function is expressed by the Hartree product. The present method is implemented into a semiempirical molecular orbital calculation program. It is demonstrated that the test calculation for a merocyanine dye well reproduces the solvatochromic shifts observed over a variety of solvents with wide ranges of dielectric constant and refractive index. (C) 1997 American Institute of Physics.