Ab initio study of the structural, electronic and optical properties of NaTaO₃

Abstract

Ab initio calculations were performed of the structural, electronic and optical properties of the cubic (, tetragonal (, and orthorhombic () phases of NaTaO₃ using a plane-wave pseudopotential method within the density-functional theory. Results are presented for the structural properties, electronic band structure, density of states and imaginary and real parts of the frequency-dependent linear optical response. Cubic and tetragonal NaTaO₃ both have an indirect band gap, at the R–Γ and Z–Γ points, respectively, whereas, orthorhombic NaTaO₃ has a direct band gap at the Γ–Γ point. The optical properties of NaTaO₃ were investigated by ab initio calculation under the scissor approximation. The real and imaginary parts of the dielectric function and, hence, the optical constants (such as absorption coefficient and the electron energy-loss spectrum) were calculated. This is the first quantitative theoretical prediction of optical properties, except for absorption of the orthorhombic phase, of the NaTaO₃ compound.

Keywords:

• NaTaO₃
• electronic band structure
• optical properties
• ab initio calculation
• perovskite