3 years ago

Strain and quasiparticle excitations: Optical properties of carbon nanotubes from first principles.

Christian Wagner, Jörg Schuster, André Schleife

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.

Publisher URL: http://arxiv.org/abs/1801.04712

DOI: arXiv:1801.04712v1

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