Atomistic Structures, Stabilities, Electronic Properties, and Chemical Bonding of Boron–Aluminum Mixed Clusters B₃Al _n^0/−/+ (n = 2–6)

Abstract: Neutral, anionic, and cationic B₃Al_n^0/−/+ (n = 2–6) clusters were systematically explored using density functional theory and coupled cluster CCSD(T) methods to investigate the structural evolution of small mixed aluminum–boron clusters. The lowest energy structures of these clusters were obtained using an unbiased global minimum search, and their structural growth behaviors are discussed. The three boron atoms in B₃Al_n^0/−/+ preferentially form a stable triangle, with additional Al atoms occupying the periphery of the boron triangle. For small clusters of n ≤ 3, the studied clusters show planar two–dimensional configurations. When n ≥ 4, the clusters prefer three–dimensional configurations. Average binding energies, fragmentation energies, second–order differences, HOMO–LUMO gaps, ionization potentials and electron affinities are discussed in detail. For cationic B₃Al_n⁺ (n = 2–6) clusters, the even n systems are more stable than the odd n systems, while the stabilities of neutral B₃Al_n and anionic B₃Al_n⁻ clusters do not change significantly with growing n. The infrared spectrum and photoelectron spectroscopy of these clusters are simulated, which will be useful for future experimental research. We also compare the chemical bonding of neutral B₃Al_n (n = 2–6) clusters with their ionic clusters by AdNDP analysis. Graphic Abstract: [Figure not available: see fulltext.]