  Tribological characteristics of nanotube-based nanoelectromechanical systems
(NEMS) exemplified by a gigahertz oscillator are studied. Various factors that
influence the tribological properties of the nanotube-based NEMS are
quantitatively analyzed with the use of molecular dynamics calculations of the
quality factor (Q-factor) of the gigahertz oscillator. We demonstrate that
commensurability of the nanotube walls can increase the dissipation rate, while
the structure of the wall ends and the nanotube length do not influence the
Q-factor. It is shown that the dissipation rate depends on the interwall
distance and the way of fixation of the outer wall and is significant in the
case of a poor fixation for the nanotubes with a large interwall distance.
Defects are found to strongly decrease the Q-factor due to the excitation of
low-frequency vibrational modes. No universal correlation between the static
friction forces and the energy dissipation rate is established. We propose an
explanation of the obtained results on the basis of the classical theory of
vibrational-translational relaxation. Significant thermodynamics fluctuations
are revealed in the gigahertz oscillator by molecular dynamics simulations and
analyzed in the framework of the fluctuation-dissipation theorem. Possibility
of designing the NEMS with a desirable Q-factor and their applications are
discussed on the basis of the above results.

Mesoscale and Nanoscale Physics