A theoretical study of alkaline-earthides Li(NH)M (M = Be, Mg, Ca) with large first hyperpolarizability.

With the aid of ab initio calculations at the MP2 level of theory, a novel type of alkaline-earthides, namely Li(NH)M (M = Be, Mg, Ca), has been theoretically designed and investigated. These compounds possess a similar geometric structure, in which the alkali-metal cation Li lies near the center of the cagelike (NH) complexant and the alkaline-earth anion M is located outside. All the proposed alkaline-earthides exhibit extremely large static first hyperpolarizability (β) up to 8.01 × 10 au, indicating that they can be considered as novel NLO molecules with high performance. The calculated results reveal that the alkaline-earth atom is more suitable to serve as excess electron acceptor in excess electron compounds for increasing the β value. We hope that our study can attract more research interest in alkaline-earthides and further experimental research.