Exact-exchange-based quasiparticle calculations

One-particle wave functions and energies from Kohn-Sham calculations with t he exact local Kohn-Sham exchange and the local density approximation (LDA) correlation potential [EXX(c)] are used as input for quasiparticle calcula tions in the GW approximation (GWA) 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 an essent ial to remedy a 0.7 eV underestimate of the experimental band gap within EX X(c). The accuracy of EXX(c)-based GWA calculations for the determination o f band gaps is as good as the accuracy of LDA-based GWA calculations. For t he lowest valence band width a qualitatively different behavior is observed for medium- and wide-gap materials. The valence band width of medium- (wid e-) gap materials is reduced (increased) in EXX(c) compared to the LDA. Qua siparticle corrections lead to a further reduction (increase). As a consequ ence, EXX(c)-based quasiparticle calculations give valence band widths that an generally 1-2 eV smaller (larger) than experiment for medium- (wide-) g ap materials.