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MM: Fachverband Metall- und Materialphysik
MM 35: Electronic Structure Theory: New Concepts and Developments in Density Functional Theory and Beyond
MM 35.10: Poster
Dienstag, 21. März 2017, 18:30–20:30, P2-OG4
The inapplicability of exact constraints, and a minimal two-parameter DFT+U generalisation, for self-interaction error correction — •Glenn Moynihan1, Gilberto Teobaldi2,3, and David D. O’Regan1 — 1School of Physics, CRANN and AMBER, Trinity College Dublin, Ireland. — 2Stephenson Institute for Renewable Energy and Department of Chemistry, The University of Liverpool, U.K. — 3Beijing Computational Science Research Center, China.
In approximate DFT, the self-interaction error (SIE) is a ubiquitous systematic inaccuracy responsible for underestimated insulating gaps, inaccurate dielectric properties and reaction barriers. It hinders the predictive applicability of DFT to spectroscopy, photochemistry, electrochemistry, and crystal-structure stability. It is, however, amenable to approximate correction using efficient methods such as DFT+U [1]. A calculation scheme for the Hubbard U parameters by variationally extremising a suitable functional might be desirable. but we show here that such an approach is not readily viable. Specifically, we prove that self-consistent constrained DFT [3] cannot be generalised for the non-linear constraints needed to target SIE [2]. We circumvent this using a generalised DFT+U functional, enabling the simultaneous correction of total-energies and ionization potentials, or either together with Koopmans’ condition. For the latter, we outline a practical, approximate first-principles scheme by which the required Hubbard parameter pair, U1 and U2, may be estimated. [1] H. J. Kulik, et al., Phys. Rev. Lett. 97, 103001 (2006). [2] Phys. Rev. B Rapid Comms., Accepted (2016), arXiv:1608.07320. [1] Phys. Rev. B 94, 035159 (2016).