Thermal stability of metallic single-walled carbon nanotubes: an O(N) tight-binding molecular dynamics simulation study

Abstract

Order(N) Tight-Binding Molecular Dynamics (TBMD) simulations are performed to investigate the thermal stability of (10,10) metallic Single-Walled Carbon Nanotubes (SWCNT). Periodic boundary conditions (PBC) are applied in axial direction. Velocity Verlet algorithm along with the canonical ensemble molecular dynamics (NVT) is used to simulate the tubes at the targeted temperatures. The effects of slow and rapid temperature increases on the physical characteristics, structural stability and the energetics of the tube are investigated and compared. Simulations are carried out starting from room temperature and the temperature is raised in steps of 300K. Stability of the simulated metallic SWCNT is examined at each step before it is heated to higher temperatures. First indication of structural deformation is observed at 600K. For higher heat treatments the deformations are more pronounced and the bond breaking temperature is reached around 2500K. Gradual (slow) heating and thermal equilibrium (fast heating) methods give the value of radial thermal expansion coefficient in the temperature range between 300K-600K as 0.31x10^{-5}(1/K) and 0.089x10^{-5}(1/K), respectively. After 600K, both methods give the same value of 0.089x10^{-5}(1/K). The ratio of the total energy per atom with respect to temperature is found to be 3x10^{-4} eV/K.