SKM 2021 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 16: Semiconductors: Optical, Transport and Ultrafast Properties

HL 16.1: Vortrag

Donnerstag, 30. September 2021, 11:15–11:30, H1

A Koopman's compliant exchange correlation potential for semiconductors — •Michael Lorke, Peter Deak, and Thomas Frauenheim — Universität Bremen

Density functional theory is the workhorse of theoretical materials investigations. Due to the shortcoming of (semi-)local exchange correlation potentials, hybrid functionals have been established for practical calculations to describe surfaces, molecular adsorption, and defects. These functionals operate by mixing between semi-local and Hartree-Fock exchange semi-emprically. However, their parameters have to be optimized for every material separately. To treat materials with a more physics driven approach and without the need of parameter optimization is possible with many-body approaches like GW, but at an immense increase in computational costs and without the access to total energies and hence geometry optimization. We propose a novel exchange correlation potential[1] for semiconductor materials, that is based on physical properties of the underlying microscopic screening. We demonstrate that it reprocuduces the low temperature band gap of several materials. Moreover, on the example of defects in semiconductors, it respects the required linearity condition of the total energy with the fractional occupation number, as expressed by the generalized Koopman's theorem. It is shown, that alloys can be treated with a common choice of the functional. We also show that this novel functional can be used as a kernel in linear response TDDFT to reproduce excitonic effects in optical spectra

[1] Physical Review B 102 (23), 235168 (2020)