Competition between alkalide characteristics and nonlinear optical properties in OLi3MLi3O (M = Li, Na, and K) complexes

Abstract

Alkalides possess enhanced nonlinear optical (NLO) responses due to localization of excess electrons on alkali metals. Employing MP2/6-311 + G(d) level, we design novel alkalides by placing alkali atoms (M) between two Li3O superalkalis. We notice a competition between alkalide characteristics and NLO properties in OLi3MLi3O (M = Li, Na, and K) isomers. For instance, the atomic charge on M (qM) in D2h structure is −0.58e for M = Li and its first static mean hyperpolarizablity (βo) is 1 a.u., but in C2v structure, qM = −0.12e and βo= 3.4 × 103 a.u. More interestingly, the βo value for M = K (C2v) increases to 1.9 × 104 a.u. in which qM = 0.24e. These findings may provide new insights into the design of alkalides, an unusual class of salts and consequently, lead to further researches in this direction.