Channeling of protons in single-walled carbon nanotubes based on kinetic and molecular-dynamics treatment

Abstract

A semi-classical kinetic model for the electronic response of a single-walled carbon nanotube (SWCNT) is combined with the Molecular Dynamics (MD) method to simulate propagation of fast protons through the nanotube, with the initial kinetic energies between 1 and 100keV. Instead of the continuum potential based on the Thomas–Fermi–Moliere model that was used in our previous work, we introduce here a MD simulation with the reactive empirical bond order potential to describe the atomic interaction between the incident ion and the carbon atoms on the nanotube wall by considering the exact carbon atom array near the impact position. The electronic polarization of the nanotube surface is described by the kinetic model in which the electron band structure dependent on the nanotube geometry is embodied. With the use of both the forces from carbon atoms and the dynamic image force due to the electronic polarization, the proton channeling trajectories that result from a sequence of consecutive reflections off the wall are discussed by solving Newton’s equations of motion. We find that, if the incident ion speed is not too high, the ion may be channeled in the SWCNT along helical trajectories that are established after several reflections from the wall.