Transferable screened range-separated hybrids for layered materials

The optoelectronic properties of layered semiconductors can vary significantly between bulk (3D) phases and their single- or few-layer, 2D counterparts. In particular, the vastly different asymptotic behavior of dielectric screening in 2D and 3D structures poses a challenge for designing screened range-separated hybrid (SRSH) functionals that are accurate for both bulk and low-dimensional systems. We present a simple yet effective approach for simultaneously tuning the fraction of short-range exact exchange and the range-separation parameter that delivers tuned SRSH functionals for 2D sheets and 3D bulk phases of layered semiconductors. The ground-state SRSH eigenvalues are found to be in excellent agreement with bandstructures from accurate, manybody GW calculations. Excited state properties are predicted using time-dependent DFT calculations, based on the SRSH functional, and are also found to be in good agreement with absorption spectra obtained from GW and Bethe-Salpeter (BSE) calculations. The ability to develop SRSH functionals that are only material- but not structure-specific opens up avenues for systematic and accurate studies of layered materials and their nanostructures at a fraction of the cost of many-body calculations.