Reliable density functional and G_0 W_0 approaches to the calculation of bandgaps in 2D materials

TL;DR

This study shows that CAM-B3LYP functional provides more reliable and consistent bandgap calculations for 2D materials when used as a starting point for G0W0 computations, improving accuracy over traditional functionals.

Contribution

The paper demonstrates that CAM-B3LYP is a superior starting point for G0W0 calculations in 2D materials, reducing deviations and improving orbital representation accuracy.

Findings

CAM-B3LYP yields minimal bandgap deviations (~0.23 eV) in G0W0 calculations.

Traditional functionals like PBE, PBE0, HSE06 show larger deviations (~1.07-1.51 eV).

CAM-B3LYP provides a better orbital representation for 2D materials.

Abstract

Optimizing density-functional theory (DFT) and G0W0 calculations present coupled problems as orbitals from DFT are needed as G0W0 starting points. Applied to 341 two-dimensional (2D) materials, we demonstrate that CAM-B3LYP provides minimal changes in bandgap (e.g., mean absolute deviation of 0.23 eV) when used to start G0W0 calculations, compared to traditional functionals such as PBE, PBE0, and HSE06 (1.07 eV, 1.48 eV, and 1.51 eV, respectively). CAM-B3LYP also delivers the smallest changes in orbital representation. These and other results indicate the suitability of CAM-B3LYP as a density-functional approach for modelling 2D materials, as well as for use in optimizing G0W0 calculations. Our findings parallel well established features of applications to molecules, as well as for spectroscopic applications involving 3D materials.