Abstract
We investigate quasiparticle band structures of rutile and anatase phases of and cubic using various levels of approximations such as , and . It is found that the quasiparticle band gap increases as the self-consistency level is ratcheted up from to and , and the results overestimate the band gap by in comparison with the experimental values. Interestingly, when the wave functions are updated in and , the band gap is significantly reduced, which is opposite to the tendency known for other materials. The experimental band gap is most closely reproduced by within error. We explain the improvement by the wave-function update in terms of the local change in the charge density, which is different at Ti and O sites and reduces the quasiparticle energy gap.
- Received 3 September 2014
- Revised 27 February 2015
DOI:https://doi.org/10.1103/PhysRevB.91.155141
©2015 American Physical Society