Structural and electronic properties of neutral and anionic magnesium clusters doped with two barium atoms

Abstract This paper reports systematic studies of small sized magnesium clusters doped with two barium atoms in both neutral and anionic species. The search, geometric optimization, and energy correction of stable and low-energy structures were completed using CALYPSO software package and DFT calculations. The structural evolution of Ba2Mgn0/– clusters (n = 1–10) with increasing size were elucidated, and we found that most of the ground-state isomers of them inherit that of the corresponding pure Mg clusters well in terms of structure. After verifying the NBO (natural bond orbital) charge of the low-lying Ba2Mgn0/– clusters (n = 1–10), a new fact was exposed: that all the doped Ba atoms in the structures are positively charged except in Ba2Mg–. A pagoda-like most-stable cluster Ba2Mg8 with a HOMO-LUMO gap of 1.59 eV was found by relative stability analysis within the scope of our study. Further analyses of the molecular orbitals and bonding of Ba2Mg8 clusters also revealed a strong interaction between Ba-6 s and Mg-3p AOs, which may be the main reason for the high stability of Ba2Mg8. We hope our studies will provide guidance for the synthesis and application of doped Mg-based nanomaterials in the future.