Graphene-based sp2-carbon nanostructures such as carbon nanotubes and nanofibers can fail near their ideal strengths due to their exceedingly small dimensions. We have calculated the phonon spectra of graphene as a function of uniaxial tension by density functional perturbation theory to assess the first occurrence of phonon instability on the strain path, which controls the strength of a defec...

Structural properties of two representative (4,4) armchair and (6,0) zigzag boron phosphide nanotubes (BP-NTs) are studied by density functional theory (DFT) calculations. To this aim, both structures and also the equivalent layer-like structures are individually optimized; afterwards, the boron-11 and phosphorous-31 chemical shielding (CS) tensors are calculated in the optimized structures. Th...

We demonstrate that free graphene sheet edges can curl back on themselves, reconstructing as nanotubes. This results in lower formation energies than any other nonfunctionalized edge structure reported to date in the literature. We determine the critical tube size and formation barrier and compare with density functional simulations of other edge terminations including a new reconstructed Klein...

The method to obtain phonon dispersion of achiral single-wall carbon nanotubes (SWNTs) from 6× 6 matrix proposed by Mahan and Jeon has been extended to chiral SWNTs. The number of calculated phonon modes of a chiral SWNT (10, 1) is much larger than that of a zigzag one (10, 0) because the number of atoms in the translational unit cell of chiral SWNT is larger than that of an achiral one even th...

The present paper discusses the effect of manganese doping on the structural stability and electronic band gap of chiral (2, 1), armchair (3, 3), and zigzag ((6, 0) and (10, 0)) single walled GaN nanotube by using density functional theory based Atomistix Toolkit (ATK) Virtual NanoLab (VNL). The structural stability has been analyzed in terms of minimum ground state total energy, binding, and f...

Persistent currents driven by a static magnetic flux parallel to the carbon nanotube axis are investigated. Owing to the hexagonal symmetry of graphene the Fermi contour expected for a 2D-lattice reduces to two points. However the electron or hole doping shifts the Fermi energy upwards or downwards and as a result, the shape of the Fermi surface changes. Such a hole doping leading to the Fermi ...

The interplay between the broken symmetry and the boundary conditions alters profoundly the electronic properties of carbon single-wall nanotubes ~SWNTs! of finite-lengths. For SWNTs (p ,q) characterized by p 5k1l , q5k2l , 0<l<k , and k51,2, . . . , the energy gaps for finite SWNTs belonging to a given family k exhibit strikingly similar oscillating patterns for even NT sections, but the gap m...