Quasiparticle $GW$ band structures and Fermi surfaces of bulk and monolayer NbS$_2$

TL;DR

This study uses the GW approximation with the SternheimerGW method to analyze many-body effects on the electronic band structures and Fermi surfaces of bulk and monolayer NbS₂, revealing significant corrections and agreement with experiments.

Contribution

It provides detailed GW-based calculations of NbS₂'s electronic properties, including substrate effects, with comprehensive convergence analysis for future research.

Findings

Many-body effects significantly alter the band structure near the Fermi level.

Calculated results align well with recent ARPES measurements.

Screened Coulomb interactions are stronger in monolayer NbS₂.

Abstract

In this work we employ the $GW$ approximation in the framework of the SternheimerGW method to investigate the effects of many-body corrections to the band structures and Fermi surfaces of bulk and monolayer NbS$_2$. For the bulk system, we find that the inclusion of these many-body effects leads to important changes in the band structure, especially in the low-energy regime around the Fermi level, and that our calculations are in good agreement with recent ARPES measurements. In the case of a free-standing monolayer NbS$_2$, we observe a strong increase of the screened Coulomb interaction and the quasiparticle corrections as compared to bulk. In this case we also perform calculations to include the effect of screening by a substrate. We report in detail the results of our convergence tests and computational parameters, to serve as a solid basis for future studies.