However, the shortest interatomic distance is systematically larger in qtz BX than in zb-BX, accompanied by the presence of distorted tetrahedra with angles smaller and larger than the ideal angle of 109.47°. The total energy per FU is lower (higher in absolute value) in qtz BX than in zb-BX. This observation is expected from the fact that zb-BX phases are the ground state structures with E/F, largest for X = As versus X = Bi. These results, which show denser qtz BX phases with smaller volumes and higher energies than those for zb-BX, suggest that qtz BX are potential highpressure phases, as will be shown below.