I. Milošević

Phonon dispersion of graphite by inelastic x-ray scattering

We present the full in-plane phonon dispersion of graphite obtained from inelastic x-ray scattering, including the optical and acoustic branches, as well as the mid-frequency range between the

FULL SYMMETRY, OPTICAL ACTIVITY, AND POTENTIALS OF SINGLE-WALL AND MULTIWALL NANOTUBES

K

Carbon nanotubes band assignation, topology, Bloch states, and selection rules

and

Super-slippery carbon nanotubes

M

Symmetry of single-wall nanotubes

points in the Brillouin zone, where experimental data have been unavailable so far. The existence of a Kohn anomaly at the

Modified group projectors: tight-binding method

K

Symmetry and lattices of single-wall nanotubes

point is further supported. We fit a fifth-nearest neighbour force-constants model to the experimental data, making improved force-constants calculations of the phonon dispersion in both graphite and carbon nanotubes available.

Interaction between layers of the multi-wall carbon nanotubes

The full symmetry groups for all single- and multi-wall carbon nanotubes are found. As for the single-wall tubes, the symmetries form nonabelian nonsymorphic line groups, enlarging the groups reported in literature. In the multi-wall case, any type of the line and the axial point groups can be obtained, depending on single-wall constituents and their relative position. Several other consequences are discussed: quantum numbers and related selection rules, electronic and phonon bands, and their degeneracy, application to tensor properties.

Chirality dependence of the radial breathing mode: a?simple model

Various properties of the energy band structures ~electronic, phonon, etc.!, including systematic band degeneracy, sticking and extremes, following from the full line group symmetry of the single-wall carbon nanotubes are established. The complete set of quantum numbers consists of the angular and linear quasimomenta and parities with respect to the U axis and, for achiral tubes, the mirror planes. The assignation of the electronic bands is performed, and the generalized Bloch symmetry adapted eigen functions are derived. The most important physical tensors are characterized by the quantum numbers. All this enables application of the presented exhaustive selection rules. The results are discussed by some examples, e.g., allowed interband transitions, conductivity, Raman tensor, etc.

Fermi level quantum numbers and secondary gap of conducting carbon nanotubes

Abstract:The friction between the walls of multi-wall carbon nanotubes is shown to be extremely low in general, with important details related to the specific choice of the walls. This is governed by a simple expression revealing that the phenomenon is a profound consequence of the specific symmetry breaking: super-slippery sliding of the incommensurate walls is a Goldstone mode. Three universal principles of tribology, offering a recipe for lubricant selection are emphasized.