Electronic, optical and elastic properties of cubic perovskite CsPbI3: Using first principles study

Structural stability and also elastic, electronic, and optical properties of cubic perovskite CsPbI3 are calculated using the full-potential linearized augmented plane wave method (FP-LAPW) based on density functional theory (DFT). The exchange-correlation potential is evaluated using the local density approximation (LDA), generalized gradient approximation (GGA) and coupling it with modified Becke-Johnson exchange potential (mbj-GGA). The calculated structural properties such as equilibrium lattice constant, the bulk modulus and its pressure derivative are in good agreement with the available data. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young's modulus and Poisson's ratio are calculated as well. The calculations of electronic band structure and density of states demonstrate that this compound has a direct energy band gap in R symmetry point about 1.56 eV and 1.879 eV by GGA and mbj-GGA respectively. The optical diagrams such as the real and imaginary parts of dielectric function, absorption, refractive index and electron energy loss, in different pressure, are calculated in [0-15 eV] energy range.