The electronic band structures were calculated within DFT based on the Augmented Spherical Wave ASW method . The crystal input data of Table were used. The band structures are depicted in Fig. . The energy along the vertical direction is with respect to the Fermi level E F since all systems are metallic with bands crossing E F ; note that Si 2 C 4 show vanishingly small band crossing at E F . However, all three phases are far from the behavior of electronically insulating diamond with a large band gap of 5 eV. The present results on electronic band structures can be approached with those of tricarbon allotropes where two kinds of hybridizations were identified for the carbon sites.