A.V. Luzanov
The theory of dielectric medium effect upon electronic structure of
molecules has been elaborated at semiempirical level of the extended reaction
field (ERF) model. The model is characterized by allowance for electronic
(optic) and orientational polarizations concurrently. These are incorporated
into effective molecular hamiltonian H ERF in quite different
ways. This leads to a nonlinear Schrodinger equation determining many-electron
states of the molecule immersed in a continuous medium. The proposed semiempirical
approximation to H ERF allows to circumvent certain difficulties
intrinsic in the prior presentation
of the model. The method has been applied to evaluate solvatochromic
effects for pi pi* excitation of conjugated systems. It is shown
that, unlike the previous quantum-chemical approaches, the ERF computational
scheme simplified to dipole contributions is in accordance with traditional
phenomenological theories.