Inquiring into geometric structures and electronic properties of sodium doped boron clusters: DFT study of NaBn (n = 1–12) clusters

The systems of alkali metal atom doped boron have been investigative topics over the years because of their diverse configurations and unique properties. Based on this, with the assistance of the CALYPSO software facilitates the structure prediction process, our group went into the geometric structures and bonding characteristics of the NaBn (n = 1–12) clusters. From the structural analysis, the participation of the Na atom does not dramatically change the configurations of the clusters, and the NaBn (n = 1–12) clusters maintain the parallel planar configuration evolution model with the pure boron clusters. The local most stable structures emerge at n = 3, 5, 8, the NEC result shows electrons transfer from Na-3s and B-2s orbitals to B-2p orbitals, indicating the s-p hybridisation exists between Na-B, B-B atoms, and the DOS analysis also prove this point. In the subsequent bonding analysis of the NaB3 and NaB8 clusters, the high proportions of B-2s, B-2p, or Na-3s orbitals at HOMO, LUMO, demonstrate the formation of strong B-B, Na-B covalent bonds, which is the benefit to forming high stability. Last, the calculations of ICSS show, perpendicular to the boron ring plane direction, the NaB3 exhibits strong aromaticity while the NaB8 shows anti-aromaticity.