Meta-Generalized Gradient Approximations with a Dielectric Function Model in the Time-Dependent Density Functional Theory for Optical Properties of Solid Materials

Accurate and efficient prediction of optical response properties of solid materials is crucial for materials science and engineering. We present a meta-generalized gradient approximation (meta-GGA) density functional-based time- and dielectric function-dependent method for calculating optical absorption, exciton binding energy, and intrinsic exciton lifetime for bulk solids and two-dimensional (2D) monolayer materials. This method uses advanced meta-GGA functionals to describe the band structures and a dielectric function model, Bethe–Salpeter equation (mBSE), to capture the screening effect and the interaction between electrons and holes. The calculated optical absorption spectra of bulk Si, diamond, SiC, Ar, NaCl, MgO, and monolayer MoS₂ agree with experimental results. The exciton binding energies of the first prominent peak in the optical absorption spectra of the direct band gap solids Ar, NaCl, and MgO from mBSE are close to the experimental values and agree with or are better than those from standard GW-BSE. For monolayer MoS₂, mBSE predicts accurate binding energy for the first prominent peak. The calculated intrinsic exciton lifetimes for materials considered here show magnitudes of several to ∼200 ns for most of the bright excitons. The presented meta-GGA-mBSE method is established as a computationally efficient alternative for the optical properties of materials.