DOMINANT ELECTRONIC OSCILLATORS IN THE OPTICAL NONLINEARITIES OF CONJUGATED POLYENES

In the coupled-oscillator representation [Takahashi and Mukamel, J. Ch em. Phys. 100 (1994) 2366],0 the optical properties of conjugated poly mers are calculated by mapping the system into a collection of coupled normal modes representing electron-hole pairs. Optical nonlinearities are induced by anharmonic couplings among oscillators and with the ex ternal field. Tree diagrams are developed which visualize the relevant nonlinearities and dominant oscillators and provide an efficient algo rithm for computing the hyperpolarizabilities.