A theoretical investigation of structural, electronic and optical   properties of bulk copper nitrides
  We present a detailed first-principles DFT study of the equation of state (EOS), energy-optimized geometries, phase stabilities and electronic properties of bulk crystalline Cu3N, CuN and CuN2 in a set of twenty different structural phases. We analyzed different structural preferences for these three stoichiometries and determined their equilibrium structural parameters. Band-structure and density of states of the relatively most stable phases were carefully investigated. Further, we carried out GW0 calculations within the random-phase approximation (RPA) to the dielectric tensor to investigate the optical spectra of the experimentally synthesized phase Cu3N(D0_9). Obtained results are compared with experiment and with previous calculations. 
Mohammed S. H. Suleiman, Mahlaga P. Molepo and Daniel P. Joubert
cond-mat.mtrl-sci cond-mat.other physics.comp-ph