All-electron mixed basis GW calculations of TiO2 and ZnO crystals.

In transition metal oxide systems, there exists a serious discrepancy between the theoretical quasiparticle energies and the experimental photoemission energies. To improve the accuracy of electronic structure calculations for these systems, we use the all-electron mixed basis GW method, in which single-particle wave functions are accurately described by the linear combinations of plane waves and atomic orbitals. We adopt the full ω integration to evaluate the correlation part of the self-energy and compare the results with those obtained by plasmon pole models. We present the quasiparticle energies and band gap of titanium dioxide (TiO2) and zinc oxide (ZnO) within the one-shot GW approximation. The results are in reasonable agreement with experimental data in the case of TiO2 but underestimated by about 0.6-1.4 eV from experimental data in the case of ZnO, although our results are comparable to previous one-shot GW calculations. We also explain a new approach to perform ω integration very efficiently and accurately. [ABSTRACT FROM AUTHOR]