关键词: LiMg$_{n}^{-}$ clusters, crystal structure analysis by particle swarm optimization (CALYPSO), structures, electronic properties

Abstract: Bimetallic clusters have aroused tremendous interest because the property changes like structure, size, and composition have occurred. Herein, a structural search of the global minimum for anionic LiMg$_{n}^{-}$ ($n=2$-11) clusters is performed using an efficient crystal structure analysis by particle swarm optimization (CALYPSO) structural searching program with subsequent density functional theory (DFT) calculations. A great variety of low energetic isomers are converged, and the most stable ones are confirmed by comparing their total energy of each size. It is found that the LiMg$_{n}^{-}$ clusters are structurally consistent with corresponding Mg clusters anions except for LiMg$_{5}^{-}$ and LiMg$_{7}^{-}$. In all the doped clusters, the Li atom prefers to occupy the convex position. Simulated photoelectron spectra (PES), Infrared (IR), and Raman spectra of LiMg$_{n}^{-}$ could be used as an essential evidence for identifying cluster structures experimentally in the future. Stability study reveals that a tower-like structure of LiMg$_{9}^{-}$ has prominent stability and can be identified as a magic number cluster. The reason might be that there are both closed-shell 1S$^{2}$1P$^{6}$1D$^{10}$2S$^{2}$ electronic configurations and stronger Li-Mg bonds caused by sp hybridization in the LiMg$_{9}^{-}$ cluster.

Key words: LiMg$_{n}^{-}$ clusters, crystal structure analysis by particle swarm optimization (CALYPSO), structures, electronic properties