Structural Evolution and Electronic Properties of Selenium-Doped Boron Clusters SeB(n)(0/−) (n = 3–16)

A theoretical research of structural evolution, electronic properties, and photoelectron spectra of selenium-doped boron clusters SeB(n)(0/−) (n = 3–16) is performed using particle swarm optimization (CALYPSO) software in combination with density functional theory calculations. The lowest energy structures of SeB(n)(0/−) (n = 3–16) clusters tend to form quasi-planar or planar structures. Some selenium-doped boron clusters keep a skeleton of the corresponding pure boron clusters; however, the addition of a Se atom modified and improved some of the pure boron cluster structures. In particular, the Se atoms of SeB(7)(−), SeB(8)(−), SeB(10)(−), and SeB(12)(−) are connected to the pure quasi-planar B(7)(−), B(8)(−), B(10)(−), and B(12)(−) clusters, which leads to planar SeB(7)(−), SeB(8)(−), SeB(10)(−), and SeB(12)(−), respectively. Interestingly, the lowest energy structure of SeB(9)(−) is a three-dimensional mushroom-shaped structure, and the SeB(9)(−) cluster displays the largest HOMO–LUMO gap of 5.08 eV, which shows the superior chemical stability. Adaptive natural density partitioning (AdNDP) bonding analysis reveals that SeB(8) is doubly aromatic, with 6 delocalized π electrons and 6 delocalized σ electrons, whereas SeB(9)(−) is doubly antiaromatic, with 4 delocalized π electrons and 12 delocalized σ electrons. Similarly, quasi-planar SeB(12) is doubly aromatic, with 6 delocalized π electrons and 14 delocalized σ electrons. The electron localization function (ELF) analysis shows that SeB(n)(0/−) (n = 3–16) clusters have different local electron delocalization and whole electron delocalization effects. The simulated photoelectron spectra of SeB(n)(−) (n = 3–16) have different characteristic bands that can identify and confirm SeB(n)(−) (n = 3–16) combined with future experimental photoelectron spectra. Our research enriches the geometrical structures of small doped boron clusters and can offer insight for boron-based nanomaterials.