Core-hole induced misalignment between Van-Hove singularities and K-edge fine structure in carbon nanotubes

Autor(en)

Martin Unzog, Alexey Tal, Pedro Melo, Ryosuke Senga, Kazu Suenaga, Thomas Pichler, Georg Kresse

Abstrakt

We investigate the relationship between the K-edge fine structure of isolated single-wall carbon nanotubes (SWCNTs) and the Van Hove singularities (VHSs) in the conduction band density of states. To this end, we model X-ray absorption spectra of SWCNTs using the final-state approximation and the Bethe-Salpeter equation (BSE) method. Both methods can reproduce the experimental fine structure, where the BSE results improve on peak positions and amplitude rations compared to the final-state approximation. When the fine structure in the modeled spectra is related to the VHSs significant differences are found. We suggest that these differences arise due to modifications of the core exciton wavefunctions induced by the confinement along the circumference. Additionally, we analyze the character of core excitons in SWCNTs and find that the first bright excitons are Frenkel excitons while higher-lying excitons are charge resonance states. Finally, we suggest that the qualitative picture based on VHSs in the density of states holds when there is a large energy gap between successive VHSs.

Organisation(en)

Computergestützte Materialphysik, Elektronische Materialeigenschaften

Externe Organisation(en)

VASP Software GmbH, National Institute of Advanced Industrial Science and Technology (AIST), Osaka University

Seiten

1-12

Anzahl der Seiten

12

DOI

https://doi.org/10.48550/arXiv.2409.17619

Publikationsdatum

09-2024

ÖFOS 2012

103009 Festkörperphysik, 103018 Materialphysik, 103020 Oberflächenphysik

Schlagwörter

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/6e4fb3ad-7d17-40e1-aded-9f03e3b480fc