Efficient and accurate defect level modelling in monolayer MoS$_2$ via GW+DFT with open boundary conditions

TL;DR

This paper introduces a novel GW+DFT method with open boundary conditions to accurately model defect levels in monolayer MoS$_2$, improving the understanding of defect states in 2D materials.

Contribution

The paper proposes the p-GW method that avoids periodic defect interference, enabling precise defect level calculations in 2D materials.

Findings

p-GW accurately models defect levels in MoS$_2$

GW correction aligns well with experimental data

Method applicable to various 2D TMDs

Abstract

Within the framework of many-body perturbation theory (MBPT) integrated with density functional theory (DFT), a novel defect-subspace projection GW method, the so-called p-GW, is proposed. By avoiding the periodic defect interference through open boundary self-energies, we show that the p-GW can efficiently and accurately describe quasi-particle correlated defect levels in two-dimensional (2D) monolayer MoS$_2$. By comparing two different defect states originating from sulfur vacancy and adatom to existing theoretical and experimental works, we show that our GW correction to the DFT defect levels is precisely modelled. Based on these findings, we expect that our method can provide genuine trap states for various 2D transition-metal dichalcogenide (TMD) monolayers, thus enabling the study of defect-induced effects on the device characteristics of these materials via realistic simulations.