Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 71: Correlated Electrons: Poster Session

TT 71.69: Poster

Mittwoch, 18. März 2015, 15:00–18:00, Poster B

Electronic structure of substitutionally disordered systems: orbital based CPA within a pseudopotential approach — •Alexander Herbig, Rolf Heid, and Robert Eder — Institute for Solid State Physics, Karlsruhe Institute of Technology

Investigating the electronic structure of substitutionally disordered systems (e.g. doped compounds) is a challenge for density functional-based methods. A straightforward supercell approach is limited to special impurity concentrations due to its huge computational effort. In order to perform calculations at arbitrary impurity concentrations effective medium theories come into play. Among them the coherent potential approximation (CPA) has been successfully applied in the KKR-DFT-framework but rarely has been used within other DFT-frameworks. Blackman, Esterling and Berk (BEB) suggested an extension to the CPA which allows to handle off-diagonal disorder on the level of hopping-terms[1]. Based on ealier work[2], we developed a fully charge self-consistent BEB-CPA for a nonorthogonal LCAO-basis. This basis is obtained via projection from a mixed-basis pseudopotential calculation. We discuss the method itself as well as its numerical verification in comparison to model calculations for a tight binding binary alloy Hamiltonian solved by exact diagonalization. Furthermore we present first applications of the method to real materials.

[1] J.A. Blackman et al., Phys. Rev. B 4, 2412 (1971)

[2] K. Koerpenik et al., Phys. Rev. B 55, 5729 (1997)