Sie befinden Sich nicht im Netzwerk der Universität Paderborn. Der Zugriff auf elektronische Ressourcen ist gegebenenfalls nur via VPN oder Shibboleth (DFN-AAI) möglich. mehr Informationen...
Optical spectra of 2D monolayers from time-dependent density functional theory
Ist Teil von
Faraday discussions, 2020-12, Vol.224, p.467-482
Ort / Verlag
England: Royal Society of Chemistry
Erscheinungsjahr
2020
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
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 MoS
2
. We find that our protocol gives a qualitatively good description of the optical spectrum of h-BN, whereas improvements are needed for MoS
2
to describe the intensity of the excitonic peaks.
Our recently developed pure Kohn-Sham approach for the calculation of optical spectra is applied to the challenging case of 2D monolayers. Our protocol yields a qualitatively good optical spectrum for h-BN, whereas improvements are needed for MoS
2
.