Besides srs topology characterizing 3D trigonal carbon allotrope leading schematically to 3D tetrahedral C 16 with 4/5/t1 topology (Figs. 1), we established similarity with lig topology C 16 (SACADA No. 25 ref. ). The structure is represented in Fig. , and the RHS polyhedral projection illustrates further the trigonal feature. lig C 16 crystallizes in high symmetry space group I4 1 /amd No. 141. With crystal structure engineering considering the structure in a lower symmetry space group I4 1 /m (No. 88), followed by slight changes of the atomic positions in Wyckoff 16f (x,y,z) of lig C 16 , an alternative trigonal tilted C 16 novel structure with the same topology (Fig. ) was obtained and showed similarities with lig-C 16 with the same cohesive energy (-2.12 eV, Table 1 st data column). The crystal data of the fully relaxed structure are given in Table .