  We have performed Linearized Augmented Plane Wave (LAPW) calculations for
five crystal structures (alpha, dhcp, sc, fcc, bcc) of Boron which we then
fitted to a non-orthogonal tight-binding model following the Naval Research
Laboratory Tight-Binding (NRL-TB) method. The predictions of the NRL-TB
approach for complicated Boron structures such as R105 (or
\b{eta}-rhombohedral) and T190 are in agreement with recent first-principles
calculations. Fully utilizing the computational speed of the NRL-TB method we
calculated the energetic differences of various structures including those
containing vacancies using supercells with up to 5000 atoms.
