Periodic n-dependence in the lowest excitation energies of the tube-like fullerenes C60+10n

Nomura, Yasushi; Fujita, Hiroya; Narita, Susumu; Shibuya, Tai-ichi

doi:10.1016/s0009-2614(03)00814-5

Cited by 7 publications

(4 citation statements)

References 14 publications

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“…The large decrease in price-to-performance ratio of modern CPUs, along with the implementation of favorably scaling density functional algorithms has recently made it possible to perform quantum-chemical calculations on the electronic structure of large single-walled nanotube (SWNT) fragments. − Most computational solid-state and quantum-chemical studies of SWNTs have so far focused on geometric and electronic structure as well as mechanical properties. It is important to study electric and magnetic response properties as well, since they are the observables of some of the most powerful and frequently applied spectroscopic methods used for characterizing molecules.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Calculations of the ¹³C NMR Chemical Shifts in (9,0) Single-Walled Carbon Nanotubes

2004

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The electronic structure and (13)C NMR chemical shift of (9,0) single-walled carbon nanotubes (SWNTs) are investigated theoretically. Shielding tensor components are also reported. Density functional calculations were carried out for C(30)-capped and H-capped fragments which serve as model systems for the infinite (9,0) SWNT. Based on the vanishing HOMO-LUMO gap, H-capped nanotube fragments are predicted to exhibit "metallic" behavior. The (13)C chemical shift approaches a value of approximately 133 ppm for the longest fragment studied here. The C(30)-capped SWNT fragments of D(3d)/D(3h) symmetry, on the other hand, are predicted to be small-gap semiconductors just like the infinite (9,0) SWNT. The differences in successive HOMO-LUMO gaps and HOMO and LUMO energies, as well as the (13)C NMR chemical shifts, converge slightly faster with the fragment's length than for the H-capped tubes. The difference between the H-capped and C(30)-capped fragments is analyzed in some detail. The results indicate that (at least at lengths currently accessible to quantum chemical computations) the H-capped systems represent less suitable models for the (9,0) SWNT because of pronounced artifacts due to their finite length. From our calculations for the C(30)-capped fragments, the chemical shift of a carbon atom in the (9,0) SWNT is predicted to be about 130 ppm. This value is in reasonably good agreement with experimental estimates for the (13)C chemical shift in SWNTs.

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Section: Introductionmentioning

confidence: 99%

Density Functional Calculations of the ¹³C NMR Chemical Shifts in (9,0) Single-Walled Carbon Nanotubes

2004

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“…A recent density-functional study also demonstrated the incommensurability in the tube-like fullerenes up to C 180 . 16 It should be noted that the incommensurability does not take place in π tight-binding calculations. Thus, the incommensurability of the oscillation is caused by the curvature effects at the caps and the cylindrical part of the nano-capsule induced by the π and σ rehybridization.…”

Section: Resultsmentioning

confidence: 99%

“…[12][13][14][15][16][17][18] However, due to a large number of carbon atoms in nanocapsules observed experimentally, the electronic structures of the capsules with a length of 10 nm (finite-length nanotube) have not been elucidated yet. Thus, in the present work, to evaluate the critical length that gives the crossover from zero-dimensional to one-dimensional electronic properties of the finitelength nanotubes, we calculate the electronic structures of the nanotubes with lengths up to 10 nm by using the generalized tight-binding model which quantitatively reproduces electronic structures of various carbon materials.…”

Section: Introductionmentioning

confidence: 99%

Electronic Structure of Finite-Length Carbon Nanotubes: Crossover From Fullerenes to Nanotubes

Okada

2007

NANO

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Finite-size effects in armchair (n,n) carbon nanotubes are studied as a function of the tube length by using the generalized tight-binding calculations. End structures of the tubes considered here are caps formed from hemispherical pieces of Ih fullerenes and hydrogen-free open ends. It has been clarified that the dimensionality in electronic structures of the finite-length nanotubes only depends on an aspect ratio of the tube diameter to the length of the cylindrical region. The aspect ratio where the finite-length tubes exhibit one-dimensional properties is found to be about four. The results corroborate that the nanotubes with their length of 10–100 nm experimentally observed could be regarded as one-dimensional electron systems.

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“…3,4) Besides the diameter and chirality, length and cap-structure decisively affect on the electronic structures of nanotubes. [5][6][7][8][9][10][11] For instance, in the case of zigzag carbon nanotubes with hydrogenated edges, they exhibit interesting spin polarization near the edge atomic sites. 10) According to these unique structural and electronic properties, carbon nanotubes are now considering to be key constituent units for nextgeneration nanometer-scale electronic devices.…”

Section: Introductionmentioning

confidence: 99%

Electronic Properties of Capped Carbon Nanotubes under an Electric Field: Inhomogeneous Electric-Field Screening Induced by Bond Alternation

Yamanaka

Okada

2013

Jpn. J. Appl. Phys.

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Neoclassical toroidal plasma viscosity (NTV) theory in collisionless regimes in tokamaks has been well developed in the past. The NTV evaluated from the connected formula developed by Shaing et al (2010 Nucl. Fusion 50 025020) was in good agreement with the numerical results in most cases. The boundary condition in the superbanana plateau regime has been found to be important in the numerical modelling when the resonant pitch is close to the boundaries of the pitch angle space, but it was not included in the original connected formula. This generates a big discrepancy between the numerical results and those evaluated from the smoothly connected formula as the resonant pitch is close to 0 or 1. Recently, the connected formula was refined. In this paper, we present the method of how to apply this refinement for practical NTV modelling and demonstrate the improvement of this refined formula by comparing the results evaluated from it with the numerical ones. Some techniques are developed to accurately model the NTV with the refined formula. The accuracy of the results modelled from the refined formula is strongly improved over the previous formula as the resonant pitch is close to 0 or 1 and they agree very well with the numerical ones.

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Periodic n-dependence in the lowest excitation energies of the tube-like fullerenes C60+10n

Cited by 7 publications

References 14 publications

Density Functional Calculations of the ¹³C NMR Chemical Shifts in (9,0) Single-Walled Carbon Nanotubes

Density Functional Calculations of the ¹³C NMR Chemical Shifts in (9,0) Single-Walled Carbon Nanotubes

Electronic Structure of Finite-Length Carbon Nanotubes: Crossover From Fullerenes to Nanotubes

Electronic Properties of Capped Carbon Nanotubes under an Electric Field: Inhomogeneous Electric-Field Screening Induced by Bond Alternation

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Periodic n-dependence in the lowest excitation energies of the tube-like fullerenes C60+10n

Cited by 7 publications

References 14 publications

Density Functional Calculations of the 13C NMR Chemical Shifts in (9,0) Single-Walled Carbon Nanotubes

Density Functional Calculations of the 13C NMR Chemical Shifts in (9,0) Single-Walled Carbon Nanotubes

Electronic Structure of Finite-Length Carbon Nanotubes: Crossover From Fullerenes to Nanotubes

Electronic Properties of Capped Carbon Nanotubes under an Electric Field: Inhomogeneous Electric-Field Screening Induced by Bond Alternation

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Density Functional Calculations of the ¹³C NMR Chemical Shifts in (9,0) Single-Walled Carbon Nanotubes

Density Functional Calculations of the ¹³C NMR Chemical Shifts in (9,0) Single-Walled Carbon Nanotubes