Electronic and Lattice Vibrational Properties of Cubic SrHfO3 from First-Principles Calculations

The electronic structure and lattice vibrational properties of cubic SrHfO3 were investigated by first-principles calculations based on density functional theory in the framework of the local density approximation (LDA), generalized gradient approximation (GGA), and density functional perturbation theory (DFPT), respectively. The calculated equilibrium lattice constant of cubic SrHfO3 is in good agreement with available experimental and theoretical results. The results show that cubic SrHfO3 is an insulator with an indirect LDA (GGA) band gap of 3.6 (3.7) eV. Use of the screened exchange local density approximation (sX-LDA) as a functional in successive band calculation has also been performed. The band gap is predicted to be 6.27 eV within sX-LDA, in excellent agreement with the gap value of 6.1 +/- A 0.1 eV obtained from x-ray photoelectron spectroscopy. The phonon dispersion curves and LO-TO splitting of cubic SrHfO3 were also calculated. Negative phonon frequencies were observed along the M-I"-R-M line in the Brillouin zone, indicating instability of the SrHfO3 structure, consistent with previous theoretical investigation.