Effects of the Cage Number and Excess Electron Number on the Second Order Nonlinear Optical Response in Molecular All-Metal Electride Multicage Chains

Abstract

For novel all-metal electride, multicage chain structures [(Ni@Ge9) Ca3]n (n = 1–4) with all real frequencies are obtained theoretically for the first time. In the structure of n = 1, the Ni@Ge9 metal cage as the shortest chain skeleton is surrounded by nonbridge Ca atoms. In the structures of n = 2–4, Ni@Ge9 metal cages are connected by bridge Ca atom pair(s) forming new hybrid multicage chain skeletons surrounded by nonbridge Ca atoms. And interesting pull–push electron relay occurs. The chain skeleton pulls valence electrons from nonbridge Ca atoms forming skeleton polyanion, and then formed polyanion pushes remaining valence electrons of the Ca atoms forming excess electrons. The excess electron numbers are Ne = 2, 0, 4, 4 for n = 1, 2, 3, 4, respectively. It is shown that these structures with excess electrons are molecular all-metal electride multicage chains, unexpectedly, and the structure (n = 2) without excess electron is a Ca salt. For nonlinear optical (NLO) response, the electride chains have...