In this paper, we employ the sum-over-states formula to calculate the dynamic third-order nonlinear optical polarizabilities of three optical processes, third-harmonic generation, electric-field-induced second-harmonic generation, and degenerate four-wave mixing, at the ground state of aniline oligomers. The ground state configurations of these compounds are obtained by the geometrical optimizations based on the B3LYP/6-31G** level. The transition moment elements and the transition energies are obtained by using the time-dependent density functional theory at the B3LYP/6-31G* level. The calculated results show that the third-order polarizability 〈γ〉 at the ground singlet state is increasing with the increase of repeat units number N of aniline oligomers and it approaches saturation at chain length around N=7-8.
Bibliographical noteFunding Information:
This investigation was based on work supported by the National Natural Science Foundation of China under project 20373073, the Science Foundation of the Fujian Province (No. E0210028), and the Foundation of State Key Laboratory of Structural Chemistry (No. 030060).
- SOS method