  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.
