Universal relation between energy gap and dielectric constant

Fuente: arXiv
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Auteurs principaux: Onishi, Yugo, Fu, Liang
Format: Preprint
Publié: 2024
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author Onishi, Yugo
Fu, Liang
author_facet Onishi, Yugo
Fu, Liang
contents We establish a universal relation between the energy gap and the static dielectric constant for all insulating states. This relation yields an upper bound on the energy gap, which only depends on the electron density and electronic dielectric constant. We identify two types of energy gaps associated with transverse and longitudinal excitations at long wavelength, which correspond to the optical gap and the plasmon energy respectively. Their upper bounds are set by the dielectric constant and its inverse respectively. The transverse gap bound is calculated for a wide range of materials and compared with the measured optical gap. A remarkable case is cubic boron nitride, in which the direct gap reaches \SI{72}{\percent} of the bound. Our results are derived from the Kramers-Kronig relation and the $f$-sum rule, and therefore rest on general physical principles.
format Preprint
id arxiv_https___arxiv_org_abs_2401_04180
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Universal relation between energy gap and dielectric constant
Onishi, Yugo
Fu, Liang
Materials Science
Strongly Correlated Electrons
We establish a universal relation between the energy gap and the static dielectric constant for all insulating states. This relation yields an upper bound on the energy gap, which only depends on the electron density and electronic dielectric constant. We identify two types of energy gaps associated with transverse and longitudinal excitations at long wavelength, which correspond to the optical gap and the plasmon energy respectively. Their upper bounds are set by the dielectric constant and its inverse respectively. The transverse gap bound is calculated for a wide range of materials and compared with the measured optical gap. A remarkable case is cubic boron nitride, in which the direct gap reaches \SI{72}{\percent} of the bound. Our results are derived from the Kramers-Kronig relation and the $f$-sum rule, and therefore rest on general physical principles.
title Universal relation between energy gap and dielectric constant
topic Materials Science
Strongly Correlated Electrons
url https://arxiv.org/abs/2401.04180