Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 20: Poster Monday: Electronic Structure

O 20.2: Poster

Montag, 1. April 2019, 17:45–20:00, Poster F

Hybrid functionals with self-consistent density-dependent mixing — •Thorsten U. Aull, Ahmad W. Huran, and Miguel A. L. Marques — Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle (Saale) Germany

One of the most famous deficiencies of Kohn-Sham density functional theory is the systematic underestimation of band gaps when they are approximated as the difference between the Kohn-Sham eigenvalues of the highest occupied eigenstate and the lowest unoccupied one [1]. Calculations with conventional hybrid functionals result in reasonable band gaps for many materials, however, within a rather narrow window for the gap [2]. This problem is attributed and large to the fact that the mixing parameter is a constant. In the work of Marques et al. it was shown that a suitable system-dependent mixing parameter can be estimated as a functional of the density of the system at hand [2]. Thus, the amount of the Hartree-Fock exchange energy is by far not the same for every material. Since the derivation of their mixing parameter was done at the level of the exchange-correlation potential, we study the limits of the proposed mixing parameter and show the requirements for self-consistent calculations using such an approach to gain access to energetic properties.
J. Perdew, Int. J. Quantum Chem. 28, 497 (1985).
M. Marques et al., Phys. Rev. B 83, 035119 (2011).