dorsal/arxiv
View SchemaAnalysis of band-gap formation in squashed arm-chair CNT
| Authors | H. Mehrez, A. Svizhenko, M. P. Anantram, M. Elstner, T. Frauenheim |
|---|---|
| Categories | |
| ArXiv ID | physics/0503100 |
| URL | https://arxiv.org/abs/physics/0503100 |
| DOI | 10.1103/PhysRevB.71.155421 |
Abstract
The electronic properties of squashed arm-chair carbon nanotubes are modeled using constraint free density functional tight binding molecular dynamics simulations. Independent from CNT diameter, squashing path can be divided into {\it three} regimes. In the first regime, the nanotube deforms with negligible force. In the second one, there is significantly more resistance to squashing with the force being $\sim 40-100$ nN/per CNT unit cell. In the last regime, the CNT looses its hexagonal structure resulting in force drop-off followed by substantial force enhancement upon squashing. We compute the change in band-gap as a function of squashing and our main results are: (i) A band-gap initially opens due to interaction between atoms at the top and bottom sides of CNT. The $\pi-$orbital approximation is successful in modeling the band-gap opening at this stage. (ii) In the second regime of squashing, large $\pi-\sigma$ interaction at the edges becomes important, which can lead to band-gap oscillation. (iii) Contrary to a common perception, nanotubes with broken mirror symmetry can have {\it zero} band-gap. (iv) All armchair nanotubes become metallic in the third regime of squashing. Finally, we discuss both differences and similarities obtained from the tight binding and density functional approaches.
{
"annotation_id": "b9a2f393-6e8b-4ecc-8d46-408e041de10d",
"date_created": "2026-03-02T18:00:56.231000Z",
"date_modified": "2026-03-02T18:00:56.231000Z",
"file_hash": "d69c5cd127a6569973a5824ed63373c4d2c66933be5e401d10a5ec22a4933745",
"private": false,
"record": {
"abstract": "The electronic properties of squashed arm-chair carbon nanotubes are modeled\nusing constraint free density functional tight binding molecular dynamics\nsimulations. Independent from CNT diameter, squashing path can be divided into\n{\\it three} regimes. In the first regime, the nanotube deforms with negligible\nforce. In the second one, there is significantly more resistance to squashing\nwith the force being $\\sim 40-100$ nN/per CNT unit cell. In the last regime,\nthe CNT looses its hexagonal structure resulting in force drop-off followed by\nsubstantial force enhancement upon squashing. We compute the change in band-gap\nas a function of squashing and our main results are: (i) A band-gap initially\nopens due to interaction between atoms at the top and bottom sides of CNT. The\n$\\pi-$orbital approximation is successful in modeling the band-gap opening at\nthis stage. (ii) In the second regime of squashing, large $\\pi-\\sigma$\ninteraction at the edges becomes important, which can lead to band-gap\noscillation. (iii) Contrary to a common perception, nanotubes with broken\nmirror symmetry can have {\\it zero} band-gap. (iv) All armchair nanotubes\nbecome metallic in the third regime of squashing. Finally, we discuss both\ndifferences and similarities obtained from the tight binding and density\nfunctional approaches.",
"arxiv_id": "physics/0503100",
"authors": [
"H. Mehrez",
"A. Svizhenko",
"M. P. Anantram",
"M. Elstner",
"T. Frauenheim"
],
"categories": [
"physics.comp-ph",
"physics.atm-clus"
],
"doi": "10.1103/PhysRevB.71.155421",
"title": "Analysis of band-gap formation in squashed arm-chair CNT",
"url": "https://arxiv.org/abs/physics/0503100"
},
"schema_id": "dorsal/arxiv",
"source": {
"execution_id": "3e15d9ac-a6af-475f-a328-1d7e33d81a16",
"id": "arXiv Dataset IDs",
"type": "Model",
"variant": "snapshot-2026-03-01",
"version": "0.1.0"
},
"user_id": 1000002
}