For the sake of completeness, in addition to the 6-fold position, space group P6 5 22, No 179 has a 12-fold particular (12c) x, y, z position, which was considered for devising extended C 12 stoichiometry. After full geometry relaxation down to the energy minimum, the ground state parameters are given in Table , and the structure is shown in Fig. . The tetrahedral arrangement is more regular than in C 3 , C 6 , C 9 and qtz C 12 , and was found to be related to diamond-like. In fact, further analysis of the topology of C 12 revealed it to be of the lon type, i.e., lonsdaleite (hexagonal diamond). Deeper crystallographic characterization led to lonsdaleite's space group P6 3 /mmc, No 194 for C 12 characterized by a splitting of the (12c) site into three (4f) sites with parameters given in the last column of Table . Consequently, we assign to novel C 12 the label of "superlonsdaleite".