Investigation of the structural, electronic and optical properties of halide perovskites AgXBr3 (X = Ca, Sr, and Ba) using DFT framework

Using the full-potential linearised augmented plane wave approach, we examined the structural, electronic, and optical features of AgXBr3 perovskite materials (X = Ca, Sr, or Ba). The GGA-PBEsol exchange-correlation functional yields equilibrium structure parameters that match the literature. Electronic structure analysis demonstrates that the Tran-Blaha modified Becke-Johnson and screened hybrid HSE06 functionals widen the bandgap compared to GGA-PBEsol. As X's atomic size rises, its indirect fundamental bandgap lowers. The density of states diagrams, complex dielectric function, electronic energy loss function, absorption coefficient, reflectivity, extinction coefficient, and refractive index were thoroughly explored. Results show that reducing the bandgap increases the dielectric function's zero frequency limits. Origins of optical spectra peaks and characteristics have been identified.