Li2SrTa2O7 Compound: Theoretical Study of Electronic and Optical properties

The electronic structures and optical properties of Li2SrTa2O7 belongs Ruddlesden-Popper layered perovskite family are studied by first-principles self-consistent local density calculations in its orthorhombic and tetragonal phases. The exchange-correlation potential were introduced within a framework of the generalized gradient approximation (GGA). In both phases, the conduction band minimum is at the zone center while the valance band is located at H and N high symmetry points for orthorhombic and tetragonal phases, respectively. The dynamic dielectric function, optical properties such as reflectance, refractivity and extinction coefficient for two phases are reported for energy range 0-50 eV. The variation in electronic and optical properties can be interpreted to attribute to higher symmetry, coordination number or Li, Sr and Ta atoms and packing density in tetragonal phase than in orthorhombic phase.