Torsional instability of chiral carbon nanotubes

Vercosa, Daniel G.; Barros, Eduardo B.; Filho, A. G. Souza; Filho, J. Mendes; Samsonidze, Ge. G.; Saito, Riichiro; Dresselhaus, M. S.

doi:10.1103/physrevb.81.165430

Cited by 35 publications

(32 citation statements)

References 18 publications

(25 reference statements)

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“…Furthermore, similar effects are predicted for MoS 2 nanotubes and for bent graphene, indicating that the presence of a natural torsion is an intrinsic characteristic of chiral nanotubes [19,20]. We in the present work improve the extended tight-binding approach used by Vercosa et al [16] by considering that the nanotube electronic states are populated according to the Fermi-Dirac distribution with a given electronic temperature T el and a chemical potential μ (in the present work, the terms chemical potential and Fermi energy are used interchangeably so that E F ¼ μ). The total electronic energy of the nanotube is obtained by summing the energies of the populated electronic states, while the total nanotube energy is given by the sum of the total electronic energy and the energy associated with the ionic repulsion between the constituent carbon atoms.…”

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confidence: 52%

“…In a previous work [16], we demonstrate that chiral nanotubes are intrinsically twisted [17] (or naturally torsioned, as it is also called [16,18]), due to a torsional instability. This intrinsic twist is explained in terms of an electronically driven stress which causes the nanotube to twist itself in order to relax into a lower energy configuration [16]. This process indicates a coupling between the nanotube structure and its electronic population.…”

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confidence: 99%

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Fermi-Energy-Dependent Structural Deformation of Chiral Single-Wall Carbon Nanotubes

Vieira¹,

Barros²,

Vercosa³

et al. 2014

Phys. Rev. Applied

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In this work, we use an extended tight-binding approach for calculating the Fermi-energy dependence of the structural deformation of chiral single-wall carbon nanotubes (SWNTs). We show that, in general, nanotube strains occur in such a way as to avoid a net charge from being accumulated on the nanotube. We also investigate the effect of the Fermi-energy-induced strains on the electronic structure of SWNTs, showing that the optical transition energies change by up to 0.5 eV due to the induced strains and that this change is nearly independent of how the nanotube is deformed. Finally, we also consider the contribution of the electron-electron Coulomb repulsion to the total energy by using an effective regularized potential energy model. We show that the inclusion of the Coulomb repulsion leads to larger strains and smaller net charges transferred to the nanotube. DOI: 10.1103/PhysRevApplied.2.014006 The nanomechanical actuation of carbon nanotubes can be controlled by using different approaches, each relying on a different mechanism for the coupling between the nanotube mechanical properties and some other controllable parameter. Modeling the nanotube nanomechanical responses to external stimuli is usually a difficult task which depends strongly on the processes involved and the type of stimulus used. For example, a nanoelectromechanical actuator works by tuning nanotube properties through an applied external electric field. However, an electric field can affect the nanotube in several different ways, which usually cannot be captured within a simple unique model. For this reason, the most common approach is to select the stimulus process which seems to be most relevant for the particular application and to use it to model the nanotube response. For example, Witkamp, Poot, and van der Zant [1] consider a direct electrostatic (capacitive) force between a gate and a suspended multiwall carbon nanotube to explain the actuation properties observed in their devices. Indeed, there are plenty of devices based on this electrostatic approach, such as the nanotweezers produced by Kim and Lieber [2], the nanobalance developed by Poncharal et al. by no means a general model and could not be applied in geometries for which the nanotube is not suspended above the gate.Another way that a nanoelectromechanical actuator may function is by a quantum-mechanical mechanism based on the change in the lattice parameters in the presence of a charge. This process has been extensively investigated by different authors using theoretical [7][8][9][10][11] and experimental [11][12][13][14][15] techniques for both graphene and carbon nanotubes. In such cases, the usual way to model the nanomechanical actuator mechanism is to include an extra charge (positive or negative) transferred to the nanotube and to optimize the carbon nanotube structure in order to balance the increased electronic energy [9,10]. Although this procedure can give interesting insights into the nanomechanical actuation of the carbon nanotubes, it is not the most appropri...

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supporting

confidence: 52%

mentioning

confidence: 99%

Fermi-Energy-Dependent Structural Deformation of Chiral Single-Wall Carbon Nanotubes

Vieira¹,

Barros²,

Vercosa³

et al. 2014

Phys. Rev. Applied

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“…In the case of CNTs, the origin of the intrinsic twist was attributed 35 to the well known sensitivity of the electronic states to torsion 38 . The BN and ZnO NT studied here exhibit lack of electronic states sensitivity to chirality and twist.…”

Section: Discussionmentioning

confidence: 99%

Helical BN and ZnO nanotubes with intrinsic twisting: An objective molecular dynamics study

2011

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We investigate helical single-walled nanotubes of BN and ZnO described with density functional based tight-binding models. The employed objective molecular dynamics computational framework accounts for the helical instead of the translational symmetry and allows for simulating chiral nanotubes as the result of the nanomechanical process of a nearly-axial glide 2 . At large diameters, by comparing the microscopic strain stored in the tube wall with the continuum predictions, we observe the invalidity of the continuum shell idealization of the one-athom thick layer. At small diameters, by comparing the computed Eshelby twist executed by the one-atom thick layers with the one predicted by pure rolling of the mono-layer, we find that a large catalog of nanotubes store intrinsic twists. This unusual intrinsic twist effect is shown to be dependent on chirality and diameter, as part of the general trend to depart from the standard rolled-up construction. While changes in the electronic structures and Young's modulus are dominated by curvature, the shear elastic constants vary both with curvature and chirality.

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“…16 With the expansion of tube on radial direction, more metal atoms are encapsulated and the number of concentric layers increases from one to three. It should be noted that single atomic chains appear only in the centers of (10, 5), (14,7) and (18, 9) tubes, demonstrating the influence of tube radius on the microstructure of internal metal clusters.…”

Section: Resultsmentioning

confidence: 97%

“…One kind of natural torsion, which can be attributed to the lack of inversion symmetry in chiral tubes by their helical structure, is investigated in chiral singlewalled CNTs with small diameters. 7 To provide a better description about this kind of chirality dependency or structural asymmetry, a molecular based anisotropic shell model is developed for predicting the mechanical behavior of CNTs. 8 Another interesting phenomenon of chiral tubes is the torsion induced by axial tension or compression.…”

Section: Introductionmentioning

confidence: 99%

Coupling Mechanical Behavior of Chiral Carbon Nanotubes Filled by Metal Atoms

Wang¹,

Kong²

2012

Jnl of Comp & Theo Nano

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Using molecular dynamics method, the induced torsional behavior of single-walled carbon nanotubes filled with copper atoms is investigated under axial tension and compression. Results show that this coupling response between torsional deformation and axial strain is only limited to chiral filled tubes. As compared with the behavior of empty chiral tubes, due to the van der Waals interaction between tube wall and the encapsulated metal atoms, the induced torsional behavior of chial filled tubes is reversed and its diameter dependency is contrary. These results can provide helpful guidelines for the applications where carbon tubes serve as torsional devices.

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Torsional instability of chiral carbon nanotubes

Cited by 35 publications

References 18 publications

Fermi-Energy-Dependent Structural Deformation of Chiral Single-Wall Carbon Nanotubes

Fermi-Energy-Dependent Structural Deformation of Chiral Single-Wall Carbon Nanotubes

Helical BN and ZnO nanotubes with intrinsic twisting: An objective molecular dynamics study

Coupling Mechanical Behavior of Chiral Carbon Nanotubes Filled by Metal Atoms

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