Using the crystal parameters in Table , the electronic band structures were obtained for both C 20 and C 8 using the all-electrons DFT-based augmented spherical wave method (ASW) and GGA exchange-correlation XC approximation of Perdew et al. . The band structures are displayed in Figure . The bands develop along the main directions of the respective BZ's. Along the vertical direction both panels exhibit the large energy gap of ~5 eV known for diamond and the zero energy is then considered at the top of the valence band, E V . Also, alike diamond, the nature of the band gap is indirect in C 20 .