Berlin 2008 – wissenschaftliches Programm

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SYEC: Symposium Exact-exchange and hybrid functionals meet quasiparticle energy calculations

SYEC 3: Exact-exchange and hybrid functionals meet quasiparticle energy calculations III - Poster (joined by SYMS posters)

SYEC 3.4: Poster

Donnerstag, 28. Februar 2008, 18:30–19:30, Poster F

Implementation of the non-local exchange potential within the FLAPW method — •M. Betzinger, C. Friedrich, G. Bihlmayer, and S. Blügel — Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany

Hybrid functionals (e.g. PBE0, B3LYP) are currently explored as a practical approximation to the exchange-correlation functional in density-functional theory (DFT). They yield accurate results for molecules, improve the band gap of semiconductors and insulators as well as the description of strongly correlated systems. So far most of the implementations for periodic systems employ pseudopotentials with a plane-wave basis set, which restricts their range of applicability. We develop an implementation within the full-potential linearized augmented plane-wave method (FLAPW), with which a much wider range of materials can be treated. The crucial step is the evaluation of the non-local exchange potential. Our approach uses a mixed basis-set. After representing the Coulomb interaction in this basis, the exchange matrix elements can be written as a Brillouin-zone (BZ) integral over vector-matrix-vector products. The Coulomb interaction goes to infinity in the center of the BZ leading to a divergence in the integrand. The divergent part is separated from the numerical integration and treated analytically. We show convergence properties of the mixed basis-set and first results for prototype semiconductors and insulators.
Financial support from the Deutsche Forschungsgemeinschaft through the Priority Program 1145 is gratefully acknowledged.