Theoretical study on the second-order nonlinear optical properties of gold (III) alkyl complexes

The equilibrium geometries of gold (III) alkyl complexes are optimized by DFT/B3LYP method. On the basis of the optimized structures, the electronic structures and second-order nonlinear optical properties are calculated by using time-dependent density-functional theory (TDDFT) combined with the sum-over-states (SOS) method. The results show that these complexes possess remarkably larger molecular second-order polarizabilities compared with the typical organometallic and organic complexes. The analysis suggests that charge transfer from the z-axis directions plays a key role in the second-order nonlinear optical response. Moreover, different ancillary ligands can substantially adjust the second-order nonlinear optical response. Thus, it can be concluded that these complexes will be hopeful candidates for the second-order nonlinear optical materials from the standpoint of high transparency, relatively large β values and small dispersion behaviors.