The electronic band structures are presented in Fig. . As in the case of phonons band structures, the bands dispersions are along the main directions of the respective Brillouin zones. Along the y-direction, the zero energy is with respect to the top of the valence band (VB), i.e. E V . The electronic band structures exhibit semi-conducting behavior with band gap magnitudes close to 0.5 eV for cubic and rhombohedral polymorphs and 1 eV for w-BP.