As for the ternary B-C-N compound, after the high-pressure synthesis of cubic BC 2 N in 2001 , the orthorhombic and trigonal structures of this compound were theoretically proposed . In the present work substitutions were made in the 4H BN polytype structure avoiding B-B and/or N-N bonds and favoring C-C and B-N bonds. Following these rules, the structure with these bonds shown in Fig. was obtained after geometry relaxation on the ground energy, and the relevant parameters are given in the last column of Table . For comparison, similarities can be observed with Fig. , which represents the trigonal BC 2 N from previous work . The interatomic distances are distributed in a range from 1.51 Å (C-N) to 1.61 Å (B-C). The structure was found to be stable with a cohesive energy between that of C 8 and BN polytypes.