Strain and screening: Optical properties of a small-diameter carbon nanotube from first principles


Strain and screening: Optical properties of a small-diameter carbon nanotube from first principles

Wagner, C.; Schuster, J.; Schleife, A.

Carbon nanotubes (CNTs) are a one-dimensional material system with intriguing physical properties that lead to emerging applications:One example is their optical-absorption spectrum, that is highly strain dependent, while, at the same time, CNTs are unusually strain-resistant compared to bulk materials.It is a largely open question, as to what extent this effect is attributed to the physics of strain-dependent (i) electronic single-particle transitions, (ii) dielectric screening, or (iii) atomic geometries including CNT radii.To explain the influence of strain on the screened Coulomb interaction in one-dimensional systems, we report on cutting-edge first-principles theoretical spectroscopy of the strain-dependent electronic structure and optical properties of an (8,0) CNT.Quasiparticle effects are taken into account using Hedin's $GW$ approximation and excitonic effects are described by solving a Bethe-Salpeter-equation for the optical-polarization function.This provides an accurate description of the electron-electron interaction and the influence of strain on dielectric screening as well as electronic structure and optical absorption.We interpret our thoroughly converged first-principles data in terms of an existing scaling relation and facilitate wide-spread use of this relation: We show that it captures strain-dependent optical absorption with satisfactory accuracy, as long as screening, the quasiparticle band gap, and effective electron and hole masses of the strained system are known.

Keywords: carbon nanotubes; optical properties; excitons; strain; first-principles calculations; density functional theory; many-body perturbation theory; screening

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Permalink: https://www.hzdr.de/publications/Publ-27762
Publ.-Id: 27762