Structural, mechanical, electronic and optical properties of layered ternary nitrides SrZrN2 and SrHfN2: First-principles calculations

Using the first-principles density functional theory, we have studied the structural, elastic, mechanical, electronic and optical properties of the layered ternary nitrides SrZrN2 and SrHfN2. The calculated ground state properties of SrZrN2 and SrHfN2 are in agreement with the available experimental data. The independent elastic constants and mechanical properties have been calculated. Results show that SrZrN2 and SrHfN2 are all mechanically stable and brittle. SrZrN2 is a semiconductor with an indirect gap of 0.993 eV and that for SrHfN2 is 1.139 eV. Moreover, the complex dielectric function, refractive index, extinction coefficient, reflectivity, absorption coefficient, loss function and optical conductivity of two compounds have been calculated.