Elastic properties of carbon nanotubes and nanoropes are investigated using
an empirical force-constant model. For single and multi-wall nanotubes the
elastic moduli are shown to be insensitive to details of the structure such as
the helicity, the tube radius and the number of layers. The tensile Young's
modulus and the torsion shear modulus calculated are comparable to that of the
diamond, while the the bulk modulus is smaller. Nanoropes composed of
single-wall nanotubes possess the ideal elastic properties of high tensile
elastic modulus, flexible, and light weight.Comment: 10 page
We studied various gas molecules (NO 2 , O 2 , NH 3 , N 2 , CO 2 , CH 4 , H 2 O, H 2 , Ar) on single-walled carbon nanotubes (SWNTs) and bundles using first principles methods. The equilibrium position, adsorption energy, charge transfer, and electronic band structures are obtained for different kinds of SWNTs.Most molecules adsorb weakly on SWNTs and can be either charge donor or acceptor to the nanotubes. We find the gas adsorption on the bundle interstitial and groove sties is stronger than that on an individual tube. The electronic properties of SWNTs are sensitive to the adsorption of certain gases such as NO 2 and O 2 . Charge transfer and gas-induced charge fluctuation might significantly affect the transport properties of SWNTs. Our theoretical results are consistent with recent experiments. 73.61.Wp, 73.20.Hb, 34.50.Dy, 82.65.My Typeset using REVT E X 1 16
We use a simple picture based on the π electron approximation to study the bandgap variation of carbon nanotubes with uniaxial and torsional strain. We find (i) that the magnitude of slope of bandgap versus strain has an almost universal behaviour that depends on the chiral angle, (ii) that the sign of slope depends on the value of (n − m) mod 3 and (iii) a novel change in sign of the slope of bandgap versus uniaxial strain arising from a change in the value of the quantum number corresponding to the minimum bandgap. Four orbital calculations are also presented to show that the π orbital results are valid.Typeset using REVT E X 1-1
We show that covalent sidewall functionalization of single-wall nanotubes leads to drastic changes of nanotube
electronic states near the Fermi level. The sp3
hybridization between the functional group and nanotube induces
an impurity state near the Fermi level. The impurity state is found to be extended over a large distance (>1
nm) even though the structural deformation is confined to the vicinity of the functionalizing site. Thus, dramatic
changes in the conductive properties of the nanotube can be expected even if the concentration of
functionalization molecules is small. This effect provides an effective pathway for band structure engineering,
nanoelectronic device, and sensor applications through covalent sidewall functionalization.
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