Evolution of the structures and stabilities of boron-doped lithium cluster cations: ab initio and DFT studies

Abstract

The lowest-energy structures and stabilities of the BLi_n⁺ (n = 1–7) cluster cations are reported using the B3LYP, MP2, and CCSD(T) methods with the 6-311+G(d) basis set. The first three-dimensional ground state in BLi_n⁺ occurs for BLi₅⁺ and the impurity, B atom, is seen to be trapped in an Li cage from BLi₅⁺ onwards. Significant changes occur for BLi_n⁺ (n = 2–4) when compared with their corresponding neutral clusters. However, there is very little change between the geometries of neutral and charged clusters for BLi₆⁺ and BLi₇⁺. The evolution of the binding energies, vertical and adiabatic electron affinities, and dissociation enthalpies with the size of BLi_n⁺, show an especial stability for BLi₆⁺ among BLi_n⁺ cluster cations. The unique stability of the 8-valence electron BLi₆⁺ can be understood from the cluster electronic shell model (CSM).