A computational study on the endohedral alkali metal and ion B40 nanocluster

Recent exploration of the boron fullerenes has raised exciting new prospects for boron applications. Here, the endohedral X/X+@B-40 complexes (X = Li, Na, and K) were explored by means of density functional theory calculations. By increasing the atomic number, the interaction of alkali metals with the B-40 nanocage is unusually weakened. It was concluded that by increasing the alkali metals' size, their electrons repel those of the cage, and the interaction weakens. The interaction of X with B-40 is more favorable than that of X+. For example, the calculated Delta G of interaction at 298 K and 1 atm is about -108.3 and + 18.4 kJ mol(-1) for X and X+, respectively. Compared to the X+ cations, the X atoms considerably enhance the boron cluster electrical conductivity, by reducing the gap. We found that the B-40 nanocluster is not large enough to freely embed large atoms, such as Na and K. Also, the electron emission from the surface of B-40 cluster is increased and reduced by X and X+ encapsulations, respectively.