Regensburg 2019 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 23: Methods in Computational Materials Modelling (methodological aspects, numerics)

MM 23.9: Talk

Wednesday, April 3, 2019, 12:30–12:45, H44

Limitations of the DFT–1/2 method for covalent semiconductors and transition-metal oxides — •Jan Doumont, Fabien Tran, and Peter Blaha — Institute of Materials Chemistry, Vienna University of Technology, Getreidemarkt 9/165-TC, A-1060 Vienna, Austria

The DFT–1/2 method in density functional theory [L. G. Ferreira et al., Phys. Rev. B 78, 125116 (2008)] aims to provide accurate band gaps at the computational cost of semilocal calculations. The method has shown promise in a large number of cases, however some of its limitations or ambiguities on how to apply it to covalently bonded semiconductors have been pointed out recently [K.-H. Xue et al., Comput. Mater. Science 153, 493 (2018)]. In this work, we investigate in detail some of the problems of the DFT–1/2 method with a focus on two classes of materials: covalently bonded semiconductors and transition-metal oxides. We argue for caution in the application of DFT–1/2 to these materials. Specifically, two conditions must be met for a reliable application: the electron density close to the valence band maximum must be sufficiently similar to the atomic orbital used to calculate the DFT–1/2 correction potential and the orbitals at the valence band maximum and conduction band minimum must be well separated in real space.