Molecular Orbitals and Third-Harmonic Generation for Symmetrically Substituted Benzylidene Aniline

Abstract

Molecular orbitals and third-order susceptibility are calculated for terephthal-bis-(4-N,N-diethylamino aniline). The main mechanism of third-harmonic generation is explained approximately by a three-level system. The effect of the orbital shape upon the susceptibility is analyzed. It is found that molecular orbital distortion, due to introduced nitrogen atoms, enhances the transition moment between excited states, 1Bu-2Ag, and this contributes to the third-order susceptibility.