Li+(3)Mg−: A new alkaline earthide with large nonlinear optical response

Abstract

Alkali metal doping has been identified as a vital step in facilitating an increase in the first hyperpolarizability(β0). To further explore this concept, we utilized Calix (Zhang et al., 2018) [3]pyrrole (3), Calix (Ma et al., 2017) [4]pyrrole (4), and Calix (Aloraini et al., 2022) [5]pyrrole (5) as our three ligands in this study. The choice of these ligands was based on their ability to undergo alkali metal doping, which ultimately led to an enhancement in the first hyperpolarizability. By doping alkali metal lithium, three new compounds Li@3, Li@4 and Li@5 were theoretically designed. Then the alkaline earthide Mg was doped onto the Li@3, and a new alkaline earthide compound Li+(3)Mg− was designed. The geometric structure and nonlinear optical properties of the molecules were studied using the CAM-B3LYP functional. The results show that Li+(3)Mg− has a considerable first-order hyperpolarizability, β0 = 21401 au, The β0 value for the 3 system is merely 37 au, whereas for the Li@3 system, it reaches a high of 12257 au Li+(3)Mg− exhibits a β0 value that is over 500 times greater than that of 3. It is evident that the electronic structure and nonlinear optical properties are significantly affected by the presence of alkali metal and alkaline earthide atoms doped in 3. The excess electron derived from alkali metal atoms and alkaline earthide atoms are significant contributors to the sudden increase in the β0 within Li+(3)Mg−. We sincerely hope that the development and production of materials with nonlinear optical properties in this study can provide new ideas and methods for the innovation of electride.