First principles study ofα-boron: can the B12cage host hetero-atoms?

The peculiar electronic and structural properties of elemental boron are studied with first principles calculations including both density functional theory and wave-function based approaches. Interaction between boron and atomic hydrogen and lithium, is considered. In particular trapping a hetero-atom, such as hydrogen or lithium in a B12 icosahedral cage, proceeds by a highly endothermic reaction and induces structural and bonding rearrangement of the host boron lattice. The peculiar charge distribution of the B12 icosahedron favours bonding that points radially outwards from the icosahedral centre.