Structures, Electronic, and Spectral Properties of Doped Boron Clusters MB₁₂ ^0/- (M = Li, Na, and K)

Structures and electronic properties of alkali metal atom-doped boron clusters MB₁₂ ^0/- (M = Li, Na, K) are determined using the CALYPSO method for the global minimum search followed by density functional theory. It is found that the global minima obtained for the neutral clusters correspond to the half-sandwich structure and those of the monoanionic clusters correspond to the boat-shaped structure. The neutral MB₁₂ (M = Li, Na, K) can be considered as a member of the half-sandwich doped B₁₂ clusters, and the geometrical pattern of anion MB₁₂ ^- (M = Li, Na, K) is a new structure that is different from other doped B₁₂ clusters. Natural population and chemical bonding analyses reveal that the alkali metal atom-doped boron clusters MB₁₂ ^- are characterized as charge transfer complexes, M⁺B₁₂ ^2-, resulting in symmetrically distributed chemical bonds and electrostatic interactions between cationic M⁺ and boron atoms. The calculated spectra indicate that MB₁₂ ^0/- (M = Li, Na, K) has meaningful spectral features that can be compared with future experimental data. Our work enriches the varieties of geometrical structures of doped boron clusters and can provide much insight into boron nanomaterials.