Transferable screened range-separated hybrid functionals for electronic and optical properties of van der Waals materials

TL;DR

This paper develops and tests transferable screened range-separated hybrid functionals for van der Waals materials, achieving accurate electronic and optical properties across different structural phases with a systematic parameter fitting approach.

Contribution

It introduces a method to determine SRSH functional parameters from extremal bulk and monolayer phases, enabling transferability to various low-dimensional structures.

Findings

SRSH functionals accurately reproduce GW and Bethe-Salpeter spectra.

Parameters fitted from bulk and monolayer phases transfer well to bilayers.

The approach simplifies the calculation of electronic properties in vdW materials.

Abstract

The accurate description of electronic properties and optical absorption spectra is a long-standing challenge for density functional theory. Recently, the introduction of screened range-separated hybrid (SRSH) functionals for solid-state materials has allowed for the calculation of fundamental band gaps and optical absorption spectra that are in very good agreement with many-body perturbation theory. However, since solid-state SRSH functionals are typically tuned to reproduce the properties of bulk phases, their transferability to low-dimensional structures, which experience substantially different screening than in the bulk, remains an open question. In this work, we explore the transferability of SRSH functionals to several prototypical van der Waals materials, including transition-metal sulfides and selenides, indium selenide, black phosphorus, and hexagonal boron nitride. Considering the bulk and a monolayer of these materials as limiting cases, we show that the parameters of the SRSH functional can be determined systematically, using only the band-edge quasiparticle energies of these extremal structural phases as fitting targets. The resulting SRSH functionals can describe both electronic bandstructures and optical absorption spectra with accuracy comparable to more demanding ab initio many-body perturbation theory (GW and Bethe-Salpeter equation) approaches. Selected examples also demonstrate that the SRSH parameters, obtained from the bulk and monolayer reference structures, display good accuracy for bandstructures and optical spectra of bilayers, indicating a degree of transferability that is independent of the fitting procedure.