Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 55: Density functional theory and beyond for real materials II

O 55.1: Talk

Wednesday, March 24, 2010, 15:00–15:15, H34

Accurate band gaps of semiconductors and insulators with a semilocal exchange-correlation potential — •Fabien Tran and Peter Blaha — Institute of Materials Chemistry, Vienna University of Technology, Vienna, Austria

Recently, Becke and Johnson [1] proposed a semilocal exchange potential which reproduces very well the shape of the exact exchange potential constructed from the optimized effective potential. We showed that this semilocal potential improves (albeit moderately) over the LDA and PBE potentials for the band gap of solids [2]. In order to have further improvement in the results for band gaps, we modified the Becke-Johnson potential (MBJ) [3]. This new potential leads to agreement with experiment which is very good for all types of solids we considered (e.g., wide band gap insulators, sp semiconductors, and strongly correlated 3d transition-metal oxides) and is of the same order as the agreement obtained with the hybrid functionals (e.g., HSE) or the GW methods. This semilocal exchange potential, which recovers the LDA for a constant electron density, mimics very well the behavior of orbital-dependent potentials and leads to calculations which are barely more expensive than LDA calculations. Therefore, it can be applied to very large systems in an efficient way.

[1] A. D. Becke and E. R. Johnson, J. Chem. Phys. 124, 221101 (2006). [2] F. Tran, P. Blaha, and K. Schwarz,J. Phys.: Condens. Matter 19, 196208 (2007). [3] F. Tran and P. Blaha, Phys. Rev. Lett. 102, 226401 (2009).