V.M. YARTSEV, W.-D. CHENG and D.-S. WU

Nonlinear optical properties of push-pull molecules modeled by a 6-member ring for a bridge and two sites for electroactive donor and acceptor groups are investigated. The parameters of the Hamiltonian used for these calculations include on-site energies and transfer integrals. These parameters have a clear physical meaning, can be estimated independently, and may be modified in a controlled way by molecular engineering. Average values of polarizability, first and second hyperpolarizabilities, as well as rotational invariants for a and b tensors are calculated for para-, meta-, and ortho-configurations of the model molecule as a function of energies of the electroactive groups.