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 c oupling of electrons with adiabatic vibrations, and for the interaction wit h the solvent, modeled in terms of a reaction field. Both interactions intr oduce a self-consistent term in the dimer Hamiltonian and therefore lead to a highly non-linear behavior. Exact results on the self-consistent dimer d emonstrate a large amplification of static NLO responses due to the couplin g of charge oscillations with the slow degrees of freedom associated to mol ecular vibrations and/or solvent reorientation. (C) 1999 Elsevier Science B .V. All rights reserved.