SKM 2023 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 20: Focus Session: Frontiers of Electronic-Structure Theory I (joint session O/HL)

HL 20.2: Talk

Tuesday, March 28, 2023, 10:45–11:00, TRE Ma

Screened potential in two-dimensional GW calculations within the LAPW framework — •Ben Alex, Sven Lubeck, and Claudia Draxl — Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany

To calculate two-dimensional (2D) materials in a three-dimensional periodic code, one has to consider periodically repeated layers. The calculation of quasiparticle energies for 2D materials within the GW approximation requires the introduction of a 2D cutoff for the Coulomb potential as the layers would otherwise interact with each other. This cutoff leads to a stronger q dependence of the dielectric function around q=0 which requires much denser sampling of the first Brillouin zone. In order to address this issue, an analytic expression for the dielectric function was previously derived for a plane-wave basis [1]. This expression is then integrated numerically in a small region around q = 0. The goal of this work is to adapt this technique to the linearized augmented planewave + local-orbital (LAPW+lo) basis as implemented in the full-potential all-electron code exciting. We show that also in our case, we obtain a significant computational speedup. Furthermore, this approach is compared with an approach where the dielectric function is interpolated to a denser q-grid.

[1] F. A. Rasmussen et al., Phys Rev B 94, 155406 (2016).