Regensburg 2016 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 71: 2D Materials beyond Graphene -Dynamics and Excitation
(Joint session of DS, DY, HL, MA, O and TT organized by O)

TT 71.4: Talk

Thursday, March 10, 2016, 11:30–11:45, S054

Understanding optical properties of atomically thin semiconductors from a many-body perspective — •Matthias Drüppel, Thorsten Deilmann, Peter Krüger, and Michael Rohlfing — Institut für Festkörpertheorie, Westfälische Wilhelms-Universität, 48149 Münster, Germany

Transition metal dichalcogenides (TMDCs) open the door to a fascinating, fast growing field of two dimensional atomically thin semiconductors. This increases the demand for novel theoretical techniques, which allow to reliably calculate the optical properties in large systems, the inclusion of substrates or even correlation between more than two particles.

We take the state of the art approach of DFT → GW → Bethe-Salpeter equation (BSE) and apply the efficient LDA+GdW [1] method. This enables us to describe many-body electronic excitations at moderate numerical cost, being able to treat systems of up to 100 atoms. In the LDA+GdW approximation the quasiparticle self-energy corrections result from the difference between the correct semiconducting screening and hypothetical metallic screening.

Our results show how the optical properties of TMDCs are modified in different situations, e.g. when the screening of the substrate is taken into account, in the presence of vacancies, or when three excited particles form a correlated trion state.

[1] M. Rohlfing, Phys. Rev. B. 82, 205127 (2010)