Long-Range Effects in Topologically Defective Arm-Chair Graphene Nanoribbons
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Título: | Long-Range Effects in Topologically Defective Arm-Chair Graphene Nanoribbons |
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Autor/es: | Louis, Enrique | Chiappe, Guillermo | Vergés Brotons, José Antonio | San-Fabián, Emilio |
Grupo/s de investigación o GITE: | Física de la Materia Condensada | Química Cuántica |
Centro, Departamento o Servicio: | Universidad de Alicante. Departamento de Física Aplicada | Universidad de Alicante. Departamento de Química Física | Universidad de Alicante. Instituto Universitario de Materiales |
Palabras clave: | Graphene | Nano-ribbons | Long-range effects |
Fecha de publicación: | 30-abr-2024 |
Editor: | MDPI |
Cita bibliográfica: | Nanomaterials. 2024, 14(9): 778. https://doi.org/10.3390/nano14090778 |
Resumen: | 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 that interact between them due to the long-range Coulomb terms of Hamiltonian. After careful analysis of the interaction among topological states, we find that the discrepancy between ab initio and model Hamiltonians can be resolved considering a screened long-range interaction that is implemented by adding an exponential cutoff to the interaction term of the 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 the Hubbard model but not completely unscreened as is the case for the PPP model. |
Patrocinador/es: | This research was funded by the Spanish “Ministerio de Ciencia e Innovación” (grant PID2019-106114GB-I00), AICO/2021/093, PROMETEO/2021/017 (“Generalitat Valenciana”) and the Universidad de Alicante. G.C. received a financial support from the Spanish Ministry of Education and Science, PID2019-109539GB-C41. |
URI: | http://hdl.handle.net/10045/142803 |
ISSN: | 2079-4991 |
DOI: | 10.3390/nano14090778 |
Idioma: | eng |
Tipo: | info:eu-repo/semantics/article |
Derechos: | © 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). |
Revisión científica: | si |
Versión del editor: | https://doi.org/10.3390/nano14090778 |
Aparece en las colecciones: | INV - QC - Artículos de Revistas INV - Física de la Materia Condensada - Artículos de Revistas |
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