Electronic and Vibrational Properties of Transition Metal-Oxides: Comparison of GGA, GGA + U, and Hybrid Approaches

We estimate the Hubbard parameters for density-functional-theory (DFT) + U calculations of ZrO₂, HfO₂, TiO₂, and NiO based on calibrating the electronic structure obtained from hybrid functional methods. The electronic density of states is used to assess the parameters and the values thus derived are employed for the full electron and phonon dispersion comparisons. The resulting values account for experimental band gaps and electron correlations that are computationally much less demanding to treat within the simpler DFT + U framework than with the typically more accurate yet expensive hybrid functional methods. Limitations of +U scheme is indicated towards describing TiO₂ and HfO₂ phase-stability.