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

Abstract

Order(N)tight-binding molecular dynamics (TBMD) simulations are performed to investigate the thermal stabilityof (10,10) metallic single-walled carbon nanotubes (SWCNTs). Periodic boundary conditions (PBCs)are applied in the axial direction. The velocity Verlet algorithm along with the canonicalensemble molecular dynamics (NVT) is used to simulate the tubes at the targetedtemperatures. The effects of slow and rapid temperature increases on the physicalcharacteristics, structural stability and the energetics of the tube are investigated andcompared. Simulations are carried out starting from room temperature and thetemperature is raised in steps of 300 K. The stability of the simulated metallic SWCNT isexamined at each step before it is heated to higher temperatures. The first indication ofstructural deformation is observed at 600 K. For higher heat treatments the deformationsare more pronounced and the bond-breaking temperature is reached around 2500 K.Gradual (slow) heating and thermal equilibrium (fast heating) methods give the value ofradial thermal expansion coefficient in the temperature range between 300 and 600 K as0.31 × 10−5 and 0.089 × 10−5 K−1, respectively. After 600 K, both methods give the same value of0.089 × 10−5 K−1. The ratio of the total energy per atom with respect to temperature is found to be3 × 10−4 eV K−1.