Hyperpolarizabilities of substituted conjugated molecules. II. Substituent effects and respective sgr;ndash;pgr; contributions

摘要

Introduced in a onehyphen;electron selfhyphen;consistent model (Dndash;C field perturbated INDO Hamiltonian), symmetry considerations exhibit sgr; and pgr; electron contributions to second order polarizabilities of planar molecules. A family of benzene monosubstitutes is explored, their mesomeric moments and pgr; second order hyperpolarizabilities are seen to account for the donor or acceptor nature of the substituent radical in accordance with a previous model and experiments. Influence of the INDO parametrization is studied for nitrobenzene, where an artificial variation of the oxygen affinity yields a satisfactory value for the benzene third order hyperpolarizability.