First-order Nonlinear Optical Response of C2Bn-2H n-1X (n = 14-17; X = H, Li, Na, K, F, Cl, Br) Carboranes: Insights from DFT and TD-DFT Calculations

Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were employed to investigate the electronic and nonlinear optical properties of some substituted C2Bn-2Hn (n = 14-17) carboranes. Li, Na, K, F, Cl, Br are used as substituents. The carboranes substituted with alkali metal show considerably large first hyperpolarizability values than those of unsubstituted ones. The nonlinear optical (NLO) response of the halogen substituted systems is slightly enhanced. The well-known two-level model theory is investigated through TD-DFT approach to understand the origin of NLO response. This study indicates that alkali-metal substituted carboranes may be appropriate for NLO applications.