Probing the effect of magnesium doping on the structural and electronic properties of boron clusters

In this paper, a global search for the lowest energy structure of Mg2Bn0/- (n = 1-12) clusters is performed based on Density functional theory combined with the particle swarm optimization algorithm program CALYPSO. The geometry, stability, charge transfer, and bonding properties of the clusters were analyzed at the B3LYP/def2-tzvp level. Then Mg2B8 with high symmetry D4h was found to be the magic numbers cluster among them. The doped clusters Mg2Bn0/- were compared with the pure boron clusters Bn+20/- (n = 1-12) at the same level. The following results are obtained: as the number of boron atoms increases, the boron clusters doped with Mg atoms change from a two-dimensional planar or quasi-plane structure to a three-dimensional structure. The doped magnesium atoms are always positively charged in the convex capped position. And the doping of Mg atoms drives the overall stabilization of the boron clusters and makes the clusters more compact. There is a large amount of charge transfer between the Mg atom and the B atom, and the main orbitals involved are the S and p orbitals. There are strong interactions between the two atoms of boron and magnesium. Through the analysis of the bonding properties, it was found that the s-p hybridization mode between Mg-B is the main reason for the enhanced cluster stability.