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MM: Fachverband Metall- und Materialphysik
MM 17: Computational Materials Modelling - Methods II
MM 17.3: Vortrag
Montag, 16. März 2020, 17:30–17:45, IFW D
Self-consistent site-dependent DFT+U(+V) for defects — Chiara Ricca1, Iurii Timrov2, Matteo Cococcioni2,3, Nicola Marzari2, and •Ulrich Aschauer1 — 1University of Bern, Bern, Switzerland — 2Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland — 3University of Pavia, Pavia, Italy
DFT calculations of defects in transition metal oxides often require advanced methods such as hybrid functionals to yield a reasonable description of the electronic structure. When properties of defects at dilute concentrations are desired, the - often incompatible - need for large supercells is added to the above functional requirement. We have recently established self-consistent, site-dependent DFT+U and DFT+U+V as promising approaches to address the challenge of simultaneously meeting these requirements. The minimal added cost of DFT+U(+V) compared to a semi-local functional enables the treatment of large supercells, yet the structural and electronic properties relevant for point-defect calculations agree well with hybrid-functionals. We ascribe this to both the self-consistent determination of the Hubbard parameters that leads to an internal consistency of results, as well as the site dependence, which for localized defect states captures chemical changes on multivalent ions around the defect. We will highlight the performance of the method for oxygen vacancies in the perovskite oxides SrTiO3 and SrMnO3. In the former self-consistent DFT+U+V leads to an electronic structure of oxygen vacancies that agrees well with that of hybrid functionals, which also translates to similar formation energies that agree well with experiment.