Umbrella-shaped vs planar; evolutionary search for BnQ, Be©BnQ (n = 6–12, Q = 0, −1) clusters

Abstract

We used the universal structure predictor: evolutionary xtallography (USPEX) method conjugated with density functional theory (DFT) calculations to investigate the global search of the neutral and anionic BnQ and Be©BnQ (n = 6–12, Q = 0,−1) clusters. The lowest- energy structures of BnQ, Be©BnQ clusters mainly featured planar or quasi-planar for all clusters, except for Be©B70/−and Be©B80/− (umbrella-shaped) clusters. Based on obtained data, it can be seen that the most stable structure of neutral and anionic clusters are the same except for B60/− and Be©B110/− clusters. Based on our calculations, the Be©B8 cluster with umbrella-shaped (heptagonal bi-pyramidal) can be observed as a magic cluster, which is extremely thermodynamic and kinetic stability. A net charge transfer from the Be metal atom to the boron motif demonstrated that the electrostatic interactions has an essential role in the stability of boron-doped clusters. Furthermore, molecular orbital (MO) and adaptive natural density partitioning (AdNDP) analyses ascertained that the enhanced stability of Be©B8 resulted from strong interactions between the 2 s orbital of Be atom and the 2s2p orbitals of the B atoms. Moreover, the B–B σ bonds in the B8 shell, which can be considered σ-anti-aromaticity and π-aromaticity, contribute to the stabilization of the Be©B8 cluster.