Table shows the crystal parameters of tet-C 6 ; the parameters of tet-C 4 are also presented for the sake of comparison. Expectedly, a larger volume characterizes tet-C 6 due to the spacing between C4 tetrahedra as schematized in Fig. . Common C1 positioned at corners and body center features both carbon structures but the introduction of C2-C2 pairs is represented by the change from twofold (2d) in tet-C 4 to four-fold (4f) in tet-C 6 . The interatomic distances are very close in both structures.