Electric-field-induced nonlinear optical switches of all-metal spherical aromatic molecules with infrared transparency: a theoretical study
Abstract
Two new all-metal molecules Be6Li8 and Be6Li14 have been designed theoretically. They possess Oh symmetric geometries and centrosymmetric electric structures. The number of their valence electrons satisfying Hirsch's rule and the highly negative nucleus independent chemical shifts at their centers reveal that they are spherical aromatic, which leads to their good chemical stabilities. When an external electric field is applied to Be6Li8 and Be6Li14, the centrosymmetry of their electric structures is broken, which brings high first hyperpolarizability (β0) contrasts. We find that β0 of Be6Li14 is larger than that of Be6Li8 under an electric field. The reason for this is that the electron density is altered more easily in Be6Li14 than in Be6Li8, which is clearly shown in the evolutions of their HOMOs with increasing electric field strength. The calculated electron spectra show that Be6Li8 and Be6Li14 have infrared transparent wavebands from 2.5 to 8.0 μm. Thus, our calculated results demonstrate that they can act as electric-field-induced infrared nonlinear optical switches.