Figure shows the electronic band structures of tet-C 4 allotrope calculated using the all-electrons DFT-based augmented spherical method (ASW) and data in Table . For the sake of comparison, the band structures of cubic diamond were calculated using the experimental lattice constant . The energy level along the vertical line is with respect to the top of the valence band (VB), E V . Like diamond, the band gap in tet-C 4 is indirect with a magnitude slightly larger than 5 eV. The electronic structure results illustrate further the closeness of tet-C 4 with diamond.