Theoretical study on the first hyperpolarizabilities of stilbene derivatives

Abstract

Static first hyperpolarizabilities of a series of stilbene derivatives are calculated at the CPHF/6-311G(d) level. the molecules which possess the electron push-pull pair and delocalized conjugated bridge structure have larger first hyperpolarizabilities because of the intramolecular charge transfer. The influence of position of the substitution, strength and number of donors and acceptors, and their coplanarity and asymmetry is discussed. The results indicate that the molecules may have larger first hyperpolarizabilities when the molecules have stronger and more donors and acceptors, large asymmetry of HOMO and LUMO, better coplanarity and higher accentricity. This work attemps at finding out the relationship between the structure and the property, thus providing theoretical basis for designing nonlinear optical molecules.