Unveiling the pressure-dependent mechanical, electronic, and optical properties of pyrite ZnTe2: DFT computations

• No phase transformation occurs in ZnTe 2 under hydrostatic pressure, unlike ZnTe. • Dynamically unstable at higher pressure but mechanically and thermally stable. • Elastic properties’ anisotropy is reduced with pressure, except linear compressibility. • Pressure causes metallization and indirect-to-direct band gap transition. • Pressure enhances absorption and broadens its spectrum in visible and UV regions. This article presents hydrostatic pressure-dependent mechanical, vibrational, electronic, and optical properties of pyrite ZnTe 2 crystal using density functional theory employing PBE, PBEsol, and HSE06 functionals. Hydrostatic pressure reduces the lattice constant and volume of the crystal while maintaining mechanical and thermodynamic stabilities within the pressure range of 0 to 4 GPa. However, the dynamic stability of the crystal is preserved up to a pressure of 2 GPa. The crystal exhibits ductility and does not experience a pressure-dependent phase transition like ZnTe. The mechanical parameters estimated by the PBE functional are slightly lower than those of the PBEsol functional. The 3D visualizations of elastic properties reveal that, except for linear compressibility, Young’s modulus, Poisson’s ratio, and shear modulus show anisotropy, which tends to reduce with increasing pressure. The crystal’s thermal stability at high temperatures is confirmed for the studied pressure range. The indirect-to-direct band transition starts at about 1 GPa and 2 GPa for the PBE and HSE06 functionals, respectively. As pressure increases, the energy bandgap decreases, eventually becoming metallic around 4 GPa for the PBE and 12 GPa for the HSE06 functional. Moreover, PBE underestimates the energy bandgap by about 0.534 eV than HSE06. The optical response of ZnTe 2 , including absorption and conductivity, covers a wide spectral range from the visible to the ultraviolet region, which is further broadened with increasing pressure. Under normal and pressure-induced conditions, the refractive index, reflectivity, and loss function of ZnTe 2 show interesting characteristics, suggesting its applications in advanced optoelectronic devices.