Coordination number effect of nitrogen atom on the structures and NLO responses: alkaline earth-based alkalides

Abstract

Alkali-doped compounds with excess electrons have been proposed to be novel candidates of high-performance nonlinear optical (NLO) materials because of their large static first hyperpolarizabilities (β 0). Can alkaline-earth-doped compounds with excess electron(s) also be good NLO materials? Our investigations on three alkaline-earth-doped compounds, i.e., Be-IAD, Be-PAD, and Be-IPD as well as a model of Be-model, indicate that the negative charge of Be and static β 0 as well as frequency-dependent β value increase with increasing the coordinated N atom number. As a result, these alkaline-earth-doped compounds not only present unusual alkaline earth-based alkalide’s features but also exhibit dramatically large static β 0 up to 2.76 × 104 au (Be-IPD), which are 317 times than that of undoped IPD, which suggests that the alkaline earth atom doping is an important method to enhance the NLO responses. These alkaline-earth-doped compounds not only present unusual alkaline earth-based alkalide’s features but also exhibit dramatically large static first hyperpolarizabilities (β 0) up to 2.76 × 104 au (Be-IPD), which are 317 times than that of undoped IPD, which suggests that the alkaline earth atom doping is an important method to enhance the NLO responses .