The gound state of boron

Elemental boron is an interesting material, both from technological and scientific point of view. At least 16 different allotropes are “known”, ranging for α rhombohedral which is well characterized and has 12 atoms in the unit cell to cubic boron of which it is only known that it contains 1708 atoms in the unit cell. For a long time discussion has been going on considering whether α rhombohedral, in which boron grows at moderate temperatures or β rhombohedral, which at high temperatures is the most stable, is the ground state at 0K. I'll present a dentisy functional theory study of these two phases and show how partial occupancies and vacancies influence the β phase and show the unexpected decisive role of zero point energy