Nonlinear Susceptabilities of Conjugated Organic Systems: Fused-ring Oligomers

Abstract

The finite-field modified neglect of diatomic overlap (MNDO) molecular orbital technique has been used to calculate the second hyperpolarisability (the molel:ular counterpart to the macroscopic nonlinear susceptability tensor X3) for selected fused-ring oligomers. The fusedring segments are the active electro-optic units in ladder polymers and rigid-rod/flexible-chain copolymers that are under current investigation as polymeric materials with applications in ultrafast optoelectronic devices.