DFT Study on Ca3AsBr3 Perovskite: Evaluation the Structural and Mechanical Stability, and Opto-electronic Properties via GGA-PBE and HSE06 Hybrid Functionals

This study provides a detailed DFT analysis of Ca3AsBr3 perovskite, assessing structural, mechanical, and optoelectronic properties using the GGA-PBE and HSE06 hybrid functionals. The optimized cubic phase (Pm-3m) with a lattice constant of 5.932 Å satisfies Born–Huang criteria, confirming mechanical stability. Electronic calculations reveal a direct bandgap of 1.58 eV (GGA) and 2.44 eV (HSE06), suitable for visible-light photovoltaic operation. The material exhibits strong absorption across the 344–574 nm range, supported by high absorption coefficients, moderate reflectivity, and favorable refractive index values (<2.0). Additionally, complex band structure and charge density analyses confirm the mixed ionic-covalent bonding nature. The dielectric constant, extinction coefficient, and optical conductivity show significant peaks around 2.8 eV, indicating strong optical performance. These results suggest Ca3AsBr3 as a robust, non-toxic, and efficient candidate for green energy applications.