Frequency-dependent hyperpolarizability of benzene derivatives: Ab-initio calculations

Structure - property relationship and dispersion effects for disubstituted benzene molecules have been investigated. Ab-initio calculations of the first hyperpolarizabilities ( beta) of donor - acceptor benzene derivatives show that the magnitude of beta depends upon the availability of the lone pair of electrons on the nitrogen atom to conjugate with the benzene ring. The HOMO - LUMO energy gap and beta have an inverse relationship. From the dispersion studies, it is observed that the first resonance peak shifts towards lower frequencies as the donor/acceptor capacity increases