Density Functional Theory: Exact Exchange: Abstract

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Exact-exchange-based quasiparticle calculations

Wilfried G. Aulbur,1 Martin Städele,2 and Andreas Görling3

1Department of Physics, Ohio State University, Columbus, OH 43210, USA
2Department of Physics, University of Illinois at Urbana-Champaign, Illinois, USA
3Lehrstuhl für Theoretische Chemie, Technische Universität München, D-85748 Garching, Germany

The first application of exact-exchange density functional theory with LDA correlation [EXX(c)] in the context of quasiparticle calculations in the GW approximation (GWA) is reported for eight semiconductors. Quasiparticle corrections to EXX(c) band gaps are small when EXX(c) band gaps are close to experiment. In the case of diamond, quasiparticle calculations are essential to remedy a 1 eV underestimation of the experimental band gap within EXX(c). The accuracy of EXX(c)-based GWA calculations for the determination of band gaps is as good as the accuracy of LDA-based GWA calculations which are known to be very accurate for sp bonded semiconductors. For the lowest valence band -- for which experimental uncertainties are as large as 1 eV -- a qualitatively different behavior is observed for medium- and wide-gap materials. The valence band width of medium- (wide-) gap materials is reduced (increased) in EXX(c) compared to LDA. Quasiparticle corrections lead to a further reduction (increase). As a consequence, EXX(c)-based quasiparticle calculations give valence band widths which are generally 1-2 eV smaller (larger) than experiment for medium- (wide-) gap materials.

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Density Functional Theory: Exact Exchange: Abstract
<http://www.physics.ohio-state.edu/~aulbur/exx/exx0.html>

Edited by: aulbur@mps.ohio-state.edu