Structural evolution and electronic properties of germanium-doped boron clusters and their anions: GeB_n^0/− (n = 6–20)

Doping is known as an effective approach to extend the knowledge of structures and properties of clusters. Herein, Ge-doped boron clusters and their anions GeB_n^0/− with n = 6–20 are systematically investigated by using a spin-polarized density functional theory method to understand their structural evolution and electronic properties. The lowest-energy structures of GeB_n and GeB_n⁻ clusters are globally searched with genetic algorithm. The doping of a Ge atom has significantly affected the growth behaviors of GeB_n^0/− clusters, leading to a structural evolution from three-dimensional configuration with a hypercoordinated Ge atom to planar or qusi-planar geometry and finally endohedral cage, in which Ge atom prefers the peripheral site or off-center position. Relative stability analysis identifies that GeB₈, GeB₁₀, GeB₁₈, GeB₇⁻, GeB₉⁻, and GeB₁₇⁻ are magic clusters. The magnetic moments of GeB_n and GeB_n⁻ clusters exhibit an evident odd–even oscillation behavior with cluster size, which is closely related to the interaction between the electronic states of Ge and B atoms. The simulated photoelectron spectra for GeB_n⁻ clusters can provide a valuable guidance for further experimental and theoretical research.