First-principles calculations to investigate variation in the bandgap of NaSrF₃ Fluoro-Perovskite with external static isotropic pressure and its Impact on optical properties

The theoretical investigation of NaSrF₃ fluoro-perovskite is carried out using ultra-soft pseudo-potential USP plane wave and Perdew Burke Ernzerhof (PBE) exchange–correlation functional of Generalized Gradient Approximation (GGA) with the help of the density functional theory-based Cambridge Serial Total Energy Package (CASTEP) code. All the properties are investigated under the effect of external static isotropic pressure ranging from 0 to 100 GPa and 300 GPa. The lattice parameters of the material are decreased with the increment of the external pressure. The value of band gap is found 4.328, 2.795, and 0 eV at 0, 100 and 300 GPa, respectively. The optical properties of the material i.e., absorption, reflectivity, dielectric function, refractive index, conductivity, and loss function are also investigated. The static values of ε₁ (ω) and n (ω) increase with the increase in pressure. It is resulted from the optical properties that the material has a high refractive index, absorption, and conductivity, and thus it is applicable in different photovoltaic systems like data storage media, and photonic crystals. Furthermore, the electronic properties of the material indicate that it operates as a semiconductor at 0 to 100 GPa while it acts as a conductor at 300 GPa.