Amplification of NLO responses: vibronic and solvent effects in push-pull polyenes

The two-state model for push-pull polyenes is extended to account for the coupling of electrons with adiabatic vibrations, and for the interaction with the solvent, modeled in terms of a reaction field. Both interactions introduce a self-consistent term in the dimer Hamiltonian and therefore lead to a highly non-linear behavior. Exact results on the self-consistent dimer demonstrate a large amplification of static NLO responses due to the coupling of charge oscillations with the slow degrees of freedom associated to molecular vibrations and/or solvent reorientation. (C) 1999 Elsevier Science B.V. All rights reserved.