Volume 224, 2020

Optical spectra of 2D monolayers from time-dependent density functional theory

Abstract

The optical spectra of two-dimensional (2D) periodic systems provide a challenge for time-dependent density-functional theory (TDDFT) because of the large excitonic effects in these materials. In this work we explore how accurately these spectra can be described within a pure Kohn–Sham time-dependent density-functional framework, i.e., a framework in which no theory beyond Kohn–Sham density-functional theory, such as GW, is required to correct the Kohn–Sham gap. To achieve this goal we adapted a recent approach we developed for the optical spectra of 3D systems [S. Cavo, J. A. Berger and P. Romaniello, Phys. Rev. B, 2020, 101, 115109] to those of 2D systems. Our approach relies on the link between the exchange–correlation kernel of TDDFT and the derivative discontinuity of ground-state density-functional theory, which guarantees a correct quasi-particle gap, and on a generalization of the polarization functional [J. A. Berger, Phys. Rev. Lett., 2015, 115, 137402], which describes the excitonic effects. We applied our approach to two prototypical 2D monolayers, h-BN and MoS2. We find that our protocol gives a qualitatively good description of the optical spectrum of h-BN, whereas improvements are needed for MoS2 to describe the intensity of the excitonic peaks.

Graphical abstract: Optical spectra of 2D monolayers from time-dependent density functional theory

Associated articles

Article information

Article type
Paper
Submitted
02 jun. 2020
Accepted
06 jul. 2020
First published
06 jul. 2020

Faraday Discuss., 2020,224, 467-482

Optical spectra of 2D monolayers from time-dependent density functional theory

S. Di Sabatino, J. A. Berger and P. Romaniello, Faraday Discuss., 2020, 224, 467 DOI: 10.1039/D0FD00073F

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements