Self-consistent DFT+U+V study of oxygen vacancies in SrTiO3
- Department of Chemistry and Biochemistry and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
- Theory and Simulation of Materials (THEOS), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
- Department of Physics, University of Pavia, Via A. Bassi 6, 27100 Pavia, Italy and Theory and Simulation of Materials (THEOS), École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
DOI10.24435/materialscloud:2020.0011/v1 (version v1, submitted on 23 January 2020)
How to cite this entry
Chiara Ricca, Iurii Timrov, Matteo Cococcioni, Nicola Marzari, Ulrich Aschauer, Self-consistent DFT+U+V study of oxygen vacancies in SrTiO3, Materials Cloud Archive (2020), doi: 10.24435/materialscloud:2020.0011/v1.
Contradictory theoretical results for oxygen vacancies (VO) in SrTiO3 (STO) were often related to the peculiar properties of STO, which is a d0 transition metal oxide with mixed ionic-covalent bonding. Here, we apply, for the first time, density functional theory (DFT) within the extended Hubbard DFT+U+V approach, including on-site as well as inter-site electronic interactions, to study oxygen-deficient STO with Hubbard U and V parameters computed self-consistently (SC) via density-functional perturbation theory. Our results demonstrate that the extended Hubbard functional is a promising approach to study defects in materials with electronic properties similar to STO. Indeed, DFT+U+V provides a better description of stoichiometric STO compared to standard DFT or DFT+U, the band gap and crystal field splitting being in good agreement with experiments.
In turn, also the description of the electronic properties of oxygen vacancies in STO is improved, with formation energies in excellent agreement with experiments as well as results obtained with the most frequently used hybrid functionals, however at a fraction of the computational cost. While our results do not fully resolve the contradictory findings reported in literature, our systematic approach leads to a deeper understanding of their origin, which stems from different cell sizes, STO phases, the exchange-correlation functional, and the treatment of structural relaxations and spin-polarization.
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23 January 2020 [This version]