First principles study of structural, electronic and elastic properties of group IB metal nitrides TMNx (TM = Cu, Ag and Au: x = 1, 2)

The structural, electronic and elastic properties of group IB transition metal nitrides (TMNx: TM = Cu, Ag, Au and x = 1, 2) are investigated by first principles calculation using the Vienna ab initio simulation package. The lattice constants, cohesive energy, bulk modulus, band structures and the density of states are obtained. The calculated lattice parameters are in good agreement with the available results. The electronic structure reveals that these materials exhibit metallic behaviour. A pressure-induced structural phase transition from NaCl to CsCl phase in AgN at 6 GPa, NaCl to ZB phase in AuN at 34.2 GPa and ZB to NaCl phase in CuN at 36.2 GPa is observed. In group IB metal di-nitrides, CaF2 to AlB2 phase transition is predicted. The computed elastic constants indicate that these nitrides are mechanically stable at ambient pressure. The calculated Debye temperature values are in good agreement with experimental and other theoretical results.