Isotropic pressure-induced electronic band structure of BaTiO3, SrTiO3 and CaTiO3 with its impact on structural and optical properties: ab-initio calculation

The present theoretical study offers a comprehensive investigation under the application of systematic external static isotropic pressure, phase stability, electronic-band structure and their impact on the optical characteristics of BaTiO3, SrTiO3 and CaTiO3. All the computational works were performed by Cambridge Serial Total Energy Package, using generalised gradient approximation and density functional theory, Perdue-Burke-Ernzerhof, along with the ultra-soft pseudo-potential for the frozen core. According to structural properties, there is no phase transformation and the structure of all compounds remains cubic. The band structure is a perfect tool to observe the nature of a material, such as an insulator, semiconductor or metal. When the pressure is applied, the band gap of BaTiO3, SrTiO3 and CaTiO3 increases and retains their indirect nature. The total/partial/elemental density of states has been estimated for the full description of the band structure. To verify the authenticity of BaTiO3, SrTiO3 and CaTiO3, various optical parameters have been reported such as the real dielectric functions, imaginary dielectric functions, absorption, refractive index, extinction coefficient, energy loss function and reflectivity. All discrepancies in structural parameters, band structure and optical properties occurred due to applied pressure, and BaTiO3, SrTiO3, and CaTiO3 are connected .