The bands develop along the main directions of the primitive hexagonal Brillouin zones. To the extent that all three phases exhibit band structures characterized by energy gaps between the valence band (VB) and the empty conduction band (CB), the energy reference along the vertical energy axis is with respect to the top of the VB: (E-E V ). qtz C 6 has a twice smaller band gap than diamond (~5 eV), showing a different behavior between dia and qtz topologies in the electronic structure behavior. The largest band gap is observed for qtz BN, which remains smaller than for cubic BN. The same feature of reduced band gap is observed for qtz SiC. It is also relevant to highlight that continuous VB in qtz C 6 versus two blocks in the binary compounds with a separation between low energy lying s-like states and higher energy lying p-like states up to E V . In conclusion, the phases with qtz topology are provided with enhanced covalence.