Regensburg 2007 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 13: Poster 1

HL 13.11: Poster

Monday, March 26, 2007, 15:00–17:30, Poster A

Efficient implementation of the exact nonlocal exchange potential within the FLAPW method — •Markus Betzinger, Christoph Friedrich, Gustav Bihlmayer, and Stefan Blügel — Institut für Festkörperphysik, Forschungszentrum Jülich, 52425 Jülich, Germany

The exact nonlocal exchange potential is an important ingredient in Hartree-Fock and density-functional calculations employing hybrid functionals (PBE0, B3LYP, etc.) as well as the optimized effective potential (OEP) (exact exchange) method. Hybrid functionals have been shown to be superior to local-density and generalized gradient-type functionals for clusters and molecules, while the OEP exchange-only approach is known to improve on the electronic band structure of semiconductors. In all methods the evaluation of the exchange potential is the most time-consuming step. While straightforward in Gaussian and plane-wave basis sets, its efficient implementation in the highly accurate full-potential linearized augmented plane-wave method (FLAPW) is still a challenge. Our approach uses a mixed basis which is specifically designed for basis-function products. After representing the Coulomb interaction in this basis, the exchange matrix elements can be written as Brillouin-zone (BZ) integrals over vector-matrix-vector products. The Coulomb interaction goes to infinity in the center of the BZ leading to a divergency in the integrand. The divergent part can be separated from the numerical integral and treated analytically. We show first results. Financial support from the Deutsche Forschungsgemeinschaft through the Priority Program 1145 is gratefully acknowledged.