Abstract
In this work, we summarize the recent progress made in constructing time-dependent density-functional theory (TDDFT) exchange-correlation (XC) kernels capable to describe excitonic effects in semiconductors and apply these kernels in two important cases: a “classic” bulk semiconductor, GaAs, with weakly-bound excitons and a novel two-dimensional material, MoS2, with very strongly-bound excitonic states. Namely, after a brief review of the standard many-body semiconductor Bloch and Bethe-Salpether equation (SBE and BSE) and a combined TDDFT+BSE approaches, we proceed with details of the proposed pure TDDFT XC kernels for excitons. We analyze the reasons for successes and failures of these kernels in describing the excitons in bulk GaAs and monolayer MoS2, and conclude with a discussion of possible alternative kernels capable of accurately describing the bound electron-hole states in both bulk and two-dimensional materials.
Highlights
Accurate theoretical description of the optical properties of materials, especially semiconductors, is very important
We present the corresponding formula for the time-dependent density-functional theory (TDDFT) susceptibility for periodic systems
A higher level of the many-body approximation to study excitons is based on the Bethe-Salpeter equation (BSE) approach [6,7,8]
Summary
Accurate theoretical description of the optical properties of materials, especially semiconductors, is very important. One can obtain such a kernel by performing straightforward differentiation of the energy functional with respect to the charge density This procedure will give an equation for the XC potential, called the optimized effective potential (OEP) (for references and details, see, e.g., [25]). We give details of the general scheme on how to calculate charge susceptibility within many-body theory and TDDFT and how to obtain the absorption spectrum using these functions. More details on this can be found, for example, in Ref. More details on this can be found, for example, in Ref. [25]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
