Barium titanate (BaTiO₃) is a perovskite based oxides with many potential application in electronic devices. From experimental report BaTiO₃ has wide energy band gap of about 3.4 eV which by doped with Ca and Zr at A-and B-sites respectively can enhance their piezoelectric properties. Using first principles method within the density functional theory (DFT) as implement in Quantum Espresso (QE) with the plane wave pseudo potential function, the influence of the Ca and Zr doping in BaTiO₃ are studied via electronic properties: band structure, total density of states (TDOS) and partial density of states (PDOS). The energy band gap calculated was underestimation which is similar to other DFT work. Two direct band gap where observed in Ba₀.₈₇₅Ca₀.₁₂₅Ti₀.₈₇₅Zr₀.₁₂₅O₃ sample at Γ-Γ (2.31 eV) and X-X (2.35 eV) symmetry point.
