Comprehensive DFT analysis of novel transition metal-based BaTiX3 (X = Cl, Br, I) halide perovskites: Structural, electronic, magnetic, optical, mechanical, and thermodynamic properties

Abstract

The Ti-based BaTiX₃ (X = Cl, Br, I) halide perovskites are investigated using DFT with the GGA-PBE functional to explore their optical, magnetic, electronic, mechanical, and thermodynamic properties. The electronic band structure and density of states reveal a metallic nature for all compounds, while phonon calculations confirm the thermal stability of BaTiI₃, with no negative lattice vibrational frequencies. Negative formation energies of −4.34, −3.87, and −3.40 eV/atom indicate thermochemical stability. Spin-polarized band structures show non-magnetic behavior. Mechanical stability is verified by Born stability criteria, and anisotropic, ductile behavior is confirmed using the anisotropic factor and Poisson’s ratio. Thermodynamic properties, including enthalpy, entropy, free energy, and heat capacity, are calculated, with zero-point energies of 0.11 eV, 0.07 eV, and 0.18 eV for BaTiX₃. Optical properties reveal all materials are active in the lower energy region. These results provide a comprehensive understanding of BaTiX₃ perovskites for advanced applications.