Narrow Results

The effect of the periodic boundary condition (PBC) on the structure and energetics of nanotubes has been investigated by performing molecular-dynamics computer simulation. Calculations have been realized by using an empirical many-body potential energy function for carbon. A single-wall carbon nanotube has been considered in the simulations. It has been found that the periodic boundary condition has no effect at low temperature (1 K), however, it plays an important role even at intermediate temperature (300 K).

We have investigated the decomposition of C₆₀ molecules with low and high coverages on Si(100)(2×1) surface at elevated temperatures. We also investigated the decomposition of an isolated C₆₀ molecule. We employed molecular-dynamics simulation using a model potential. It has been found that C₆₀ decomposes on Si(100) surface after 1000 K in the case of low coverage (0.11), however in high coverage case (0.67), C₆₀ molecules decompose after 900 K. On the other hand, isolated C₆₀ molecule decomposes after 7500 K, interestingly it shows a phase change from 3D to 2D at higher temperatures.

The structural properties of single and multi-wall carbon nanotubes and the formation of carbon nanorods from multi-wall carbon nanotubes have been investigated by performing molecular-dynamics computer simulations. Calculations have been realized by using an empirical many-body potential energy function for carbon. It has been found that carbon nanorod formation takes place with smallest possible multi-wall nanotubes under heat treatment. On the other hand, it has been also found that single-wall carbon nanotubes are stronger than the multi-wall nanotubes against heat treatment.

The structural stability of carbon nanocages, fullerens and toroids, have been investigated by performing molecular-dynamics computer simulations. The systems considered are C₁₂₀ and C₂₄₀ in ball and toroidal structures. Calculations have been realized by using an empirical many-body potential energy function for carbon. It has been found that C₁₂₀ ball is very unstable, and the other structures are relatively more strong against heat treatment.

The effect of chirality on the structural stability of single-wall carbon nanotubes have been investigated by performing molecular-dynamics computer simulations. Calculations have been realized by using an empirical many-body potential energy function for carbon. It has been found that carbon nanotube in chiral structure is more stable under heat treatment relative to zigzag and armchair models. The diameter of the tubes is slightly enlarged under heat treatment.

The structural stability of carbon nanoballs (fullerenes) C₂₀, C₆₀, and onion type C₂₀@C₆₀ has been investigated by performing molecular-dynamics computer simulations. Calculations have been realized by using an empirical many-body potential energy function for carbon. It has been found that C₂₀ is relatively resistive to heat treatment, however, the onion type structure is relatively less strong against heat treatment. The electronic structure of the systems considered has been also studied by performing density functional theory type calculations.

The formation of carbon nanorods from various types of carbon nanotubes has been investigated by performing molecular-dynamics computer simulations. Calculations have been realized by using an empirical many-body potential energy function for carbon. It has been found that carbon nanorod formed from carbon nanotubes with different chirality is not stable even at low temperature.

The structural properties of carbon nanorods obtained from diamond crystal have been investigated by performing molecular-dynamics computer simulations. Calculations have been realized by using an empirical many-body potential energy function for carbon. Diamond nanorods have been generated from three low-index planes of diamond crystal. It has been found that the average coordination number, cross-section geometry, and surface orientation from which the nanorod is generated play a role in the stability of diamond nanorods under heat treatment. The most stable diamond nanorod has been obtained from the (111) surface.

Junction formation in crossed C(10,0) single wall carbon nanotubes under pressure has been investigated, using classical molecular-dynamics simulations at 1 K. It has been found that a stable mechanical junction was formed by means of placing two crossed single wall carbon nanotubes between two rigid graphene layers which move toward each other.