Efficient External Electric Field Manipulated Nonlinear Optical Switches of All-Metal Electride Molecules with Infrared Transparency: Nonbonding Electron Transfer Forms an Excess Electron Lone Pair

Focusing on the interesting new concept of all -metal electride, centrosymmetric molecules e(-)+M2+(Ni@Pb-12)M-2-(2+)+e(-) (M = Be, Mg, and Ca) with two anionic excess electrons located at the opposite ends of the molecule are obtained theoretically. These novel molecular all-metal electrides can act as infrared (IR) nonlinear optical (NLO) switches. Whereas the external electric field (F) hardly changes the molecular structure of the all-metal electrides, it seriously deforms their excess electron orbitals and average static first hyperpolarizabilities (beta(e)(0)(F)). For e(-)+Ca2+(Ni@Pb-12)(2-) Ca2++e(-), a small external electric field F = 8 x 10(-4) au (0.04 V/angstrom) drives a long-range excess electron transfer from one end of the molecule through the middle all-metal anion cage (Ni@Pb-12)(2-) to the other end. This long-range electron transfer is shown by a prominent change of excess electron orbital-from double lobes to single lobe, which forms an excess electron lone pair and electronic structure Ca2+(Ni@P-12)(2-) Ca2++2e(-). Therefore, the small external electric field induces a dramatic beta(e)(0)(F) contrast from 0 (off form) to 2.2 x 10(6) au (on form) in all metal electride molecule Ca(Ni@Pb-12)Ca. Obviously, such switching is high sensitive. Interestingly, in the switching process, such long-range excess electron transfer does not alter the valence and chemical bond nature. Then, this switching Mechanism is, a distinct nonbonding evolution named electronic structure isomerization, which means that such switching has the advantages of being fast and reversible. Besides, these all-metal electride molecules also have a rare IR transparent characteristic (1.5-10 mu m) in NLO electride molecules, and hence are commendable molecular IR NLO switches. Therefore, this work opens a new research field of electric field manipulated IR NLO switches of molecular all-metal electrides.