Excitonic optical spectrum of semiconductors obtained by time-dependent density-functional theory with the exact-exchange kernel

TL;DR

This paper demonstrates that using the exact-exchange kernel within time-dependent density-functional theory accurately reproduces the excitonic optical spectrum of silicon, emphasizing the importance of Coulomb coupling and correct long-wavelength behavior.

Contribution

The study introduces a novel application of the exact-exchange Kohn-Sham method in TDDFT to accurately capture excitonic effects in semiconductor optical spectra.

Findings

Accurate optical absorption spectrum of silicon obtained

Inclusion of Coulomb coupling is crucial

Correct long-wavelength behavior is essential

Abstract

Applying the novel exact-exchange (EXX) Kohn-Sham method within time-dependent density-functional theory, we obtained the optical absorption spectrum of bulk silicon in good agreement with experiments including excitonic features. Analysis of the EXX kernel shows that inclusion of the Coulomb coupling of electron-hole pairs and the correct long-wavelength behavior in the kernel is crucial for the proper description of excitonic effects in semiconductors.