First-principles studies of structural and electronic properties of layered C3N phases

The structural and electronic properties of layered C3N compound have been studied using ab initio pseudopotential density-functional method within the local-density approximation. Total energy, lattice constant, band structure, and electron density of state are calculated. Among three possible C3N monolayer configurations, the monolayer-I structure with the highest symmetry is the most stable and predicted to be a narrowgap semiconductor with an indirect gap about 0.283?eV. Among four possible C3N stacking configurations constructed from hexagonal BN and graphite structures, C3N-IV constructed from hexagonal BN is expected to be the most stable structure and has metallic conducting behavior. The structural stability of layered C3N has also been checked by the calculations of the formation energies, elastic constants, and phonon frequencies.