Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 80: Challenges in semiconductor theory

HL 80.1: Talk

Thursday, March 19, 2015, 15:00–15:15, EW 015

Full exact exchange and non-local correlation - a next step on the path to a physical Kohn-Sham density of states? — •Tobias Schmidt and Stephan Kümmel — University of Bayreuth, Germany

Density Functional Theory (DFT) provides an efficient and, in principle, exact framework to calculate the electronic structure of matter. In practice, DFT results strongly depend on the exchange correlation (xc) functional used. Hybrid functionals, i.e., combining a semi-local density functional with a fixed percentage of Fock exchange, have been in widespread use. However, there is no "perfect" hybrid: Hybrids with a low (ca. 20%) percentage of Fock exchange describe binding and structural properties well, but much higher amounts of Fock-exchange (ca. 50%) are needed if one aims at eigenvalues that well approximate the density of states.

In an attempt to overcome this gap, a local hybrid functional was designed. The constant mixing parameter of usual hybrids is replaced by a density functional. Thus, full Fock exchange is combined with non-local correlation. We discuss in how far this generalization leads to results that are similar or different from the usual global hybrids. We pay particular attention to the reduction of self-interaction errors, the long-range asymptotic behavior of the potential, and whether the Kohn-Sham density of states becomes more physical. First results on practically relevant, non-trivial systems with d-electrons, e.g., Palladium particles, will be presented.