The theoretical studies on the two-photon absorption properties of symmetric 1,4-bis2-4-(2-aryl)phenylvinyl-2,5-bisdialkoxybenzenes

On the level of the time-dependent hybrid density functional theory, the one- and two-photon absorption properties of a series of symmetric 4-bis 2-4-(2-ary12) phenylvinyl-2,5-bisdialkoxybenzenes are studied respectively utilizing the analytic response theory and the few-state model methods. The calculated results show that the planarity of the geometrical structure plays a great role in enhancing the linear and nonlinear optical abilities of the molecule. However the effect of the length of the chain linked to the \pi-centre on the optical property is very little. For the investigated compounds, the A–\pi–A type charge-transfer molecules display more superior one- and two-photon absorption characteristics than the D–\pi–D type ones. Furthermore, the two-photon absorption results by use of few-state model are generally consistent with those by analytic response theory, demonstrating the reliability of the few-state model for evaluating the two-photon absorption cross section. The numerical simulations are in good agreement in tendency with the available experimental measurements.