Solid-state optical absorption from optimally-tuned time-dependent range-separated hybrid density functional theory

TL;DR

This paper introduces a new computational framework using optimally-tuned range-separated hybrid density functional theory to accurately predict optical properties and excitations in solid-state materials, matching experimental results and offering a cost-effective alternative to more complex methods.

Contribution

The paper develops a fully generalized Kohn-Sham based approach that accurately predicts exciton binding energies, band structures, and optical spectra with minimal adjustable parameters.

Findings

Accurately predicts exciton binding energies in molecular crystals.

Reproduces experimental optical spectra of silicon and lithium fluoride.

Offers a computationally inexpensive alternative to many-body perturbation theory.

Abstract

We present a framework for obtaining reliable solid-state charge and optical excitations and spectra from optimally-tuned range-separated hybrid density functional theory. The approach, which is fully couched within the formal framework of generalized Kohn-Sham theory, allows for accurate prediction of exciton binding energies. We demonstrate our approach through first principles calculations of one- and two-particle excitations in pentacene, a molecular semiconducting crystal, where our work is in excellent agreement with experiments and prior computations. We further show that with one adjustable parameter, set to produce an accurate bandgap, this method accurately predicts band structures and optical spectra of silicon and lithium flouride, prototypical covalent and ionic solids. Our findings indicate that for a broad range of extended bulk systems, this method may provide a computationally inexpensive alternative to many-body perturbation theory, opening the door to studies of materials of increasing size and complexity.