Ab initio Calculation of Structural Stability, Electronic and Optical Properties of Ag_2Se

摘要

The structural stability, electronic and optical properties of Ag_2Se compound is studied using ab initio packages. Ag_2Se is found to crystallize in orthorhombic structure with two different space groups i.e. P2_12_12_1 (No. 19) and P222_1 (No. 17). For this compound in these two space groups, the total energy has been computed as a function of volume. Our calculated results suggest that the P2_12_12_1 -phase is more stable than that of the P222_1-phase. The band structure calculation show that Ag_2Se is semimetallic with an overlap of about 0.014 eV in P2_12_12_1-phase whereas is metallic in nature in P222_1-phase. Moreover, the optical properties including the dielectric fuction, energy loss spectrum are obtained and analysed.