LAUSR

We have performed first-principles calculations within density functional theory (DFT) to investigate the hardness, elastic, thermodynamic and electronic properties of metal nitrides compounds (XN2; X = Pd, Pt) in pyrite structure, under high hydrostatic pressure. The calculated structural properties match with those previously reported experimental and theoretical data. The Vickers hardness of PdN2 and PtN2 compounds were calculated in 7.5 and 27.7 GPa, respectively. We also calculated the electronic properties of both compounds. The calculated electronic band structure of PtN2 at either 0 GPa or 153 GPa reveals that this compound is an indirect semiconductor. The top of the valence band is located at M point, whereas the bottom of the conduction band at Λ point at zero pressure or at Σ point at 153 GPa. In the case of PdN2, it was found a conductor-semiconductor transition at 104 GPa.