Version 1
: Received: 13 December 2023 / Approved: 15 December 2023 / Online: 15 December 2023 (05:32:33 CET)
Version 2
: Received: 2 April 2024 / Approved: 3 April 2024 / Online: 3 April 2024 (08:17:05 CEST)
How to cite:
Louis, E.; Chiappe, G.; Vergés, J.A.; San-Fabián, E. Long Range Effects in Topologically Defective Arm-Chair Graphene Nanoribbons. Preprints2023, 2023121125. https://doi.org/10.20944/preprints202312.1125.v2
Louis, E.; Chiappe, G.; Vergés, J.A.; San-Fabián, E. Long Range Effects in Topologically Defective Arm-Chair Graphene Nanoribbons. Preprints 2023, 2023121125. https://doi.org/10.20944/preprints202312.1125.v2
Louis, E.; Chiappe, G.; Vergés, J.A.; San-Fabián, E. Long Range Effects in Topologically Defective Arm-Chair Graphene Nanoribbons. Preprints2023, 2023121125. https://doi.org/10.20944/preprints202312.1125.v2
APA Style
Louis, E., Chiappe, G., Vergés, J.A., & San-Fabián, E. (2024). Long Range Effects in Topologically Defective Arm-Chair Graphene Nanoribbons. Preprints. https://doi.org/10.20944/preprints202312.1125.v2
Chicago/Turabian Style
Louis, E., José A. Vergés and Emilio San-Fabián. 2024 "Long Range Effects in Topologically Defective Arm-Chair Graphene Nanoribbons" Preprints. https://doi.org/10.20944/preprints202312.1125.v2
Abstract
The electronic structure of 7/9-AGNR superlattices with up to eight unit cells has been studied by means of state of the art Density Functional Theory (DFT) and also by two model Hamiltonians, the first one including only local interactions (Hubbard model, Hu) while the second one is extended to allow long-range Coulomb interactions (Pariser, Parr and Pople model, PPP). Both are solved within mean field approximation. At this approximation level, our calculations show that 7/9 interfaces are better described by spin non-polarized solutions than by spin-polarized wavefunctions. Consequently, both Hu and PPP Hamiltonians lead to electronic structures characterized by a gap at the Fermi level that diminishes as the size of the system increases. DFT results show similar trends although a detailed analysis of the density of states around the Fermi level shows quantitative differences with both Hu and PPP models. Before improving model Hamiltonians, we interpret the electronic structure obtained by DFT in terms of bands of topological states: topological states localized at the system edges and extended bulk topological states which interact between them due to the long-range Coulomb terms of Hamiltonian. After careful analysis of the interaction among topological sates, we find that the discrepancy between ab initio and model Hamiltonians can be resolved considering a screened long-range interaction that is implemented adding an exponential cutoff to the interaction term of PPP model. In this way, an adjusted cutoff distance λ = 2 allows a good recovery of DFT results. In view of this, we conclude that the correct description of the density of states around the Fermi level (Dirac point) needs the inclusion of long-range interactions well
beyond Hubbard model but not completely unscreened as is the case for the PPP model.
Keywords
graphene; nano-ribbons; long range effects
Subject
Chemistry and Materials Science, Physical Chemistry
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
