The nitrogen vacancy and oxygen substitution of OsN2: First-principles investigation

• The effect of N vacancy and O substitution on OsN2 were theoretical studied.
• Calculated formation energy shows that O substitution can stabilize marcasite OsN2.
• Calculated bulk modulus of OsN2 with O substitution is close to experimental results.

Usually, experimental bulk modulus is close to the average value of bulk modulus obtained by GGA and LDA. However, it does not happen in OsN2. For OsN2, experimental bulk modulus is even lower than that with GGA. Such case suggests that N vacancy or O substitution may exist in synthesized OsN2. We clarify this issue by calculating various properties of OsN2 with N vacancy and O substitution. Calculated formation energy shows that O substitution can stabilize marcasite OsN2. Moreover, the calculated bulk modulus of OsN2 with O substitution is close to experimental results. The N vacancy or O substitution can decrease covalent interaction of OsN2 and consequently its bulk modulus becomes lower. For OsN2, O substitution only decrease the shear modulus by 9%. The calculated density of states indicates that OsN2 with N vacancy or O substitution keep its metallic behavior.