Investigation of the Influence of Thermostat Configurations on the Mechanical Properties of Carbon Nanotubes in Molecular Dynamics Simulations

The effect of thermostat configurations on the mechanical behavior of empty and butane (n-C₄H₁₀) filled (10, 10) carbon nanotubes (CNTs) is examined using classical, atomistic, molecular dynamics (MD) simulations. In particular, the influence of different types of thermostats, relative numbers of thermostat atoms, and rates of deformation are considered. The compressive forces on the atoms are calculated using the second generation reactive empirical bond-order potential. The results indicate that use of a Langevin thermostat leads to a substantial dependency of the results of CNT compression on the number of thermostat atoms and the rate of deformation. On the other hand, the Nosé-Hoover and the velocity rescaling thermostats exhibit consistent mechanical responses during CNT compression regardless of the relative number of thermostat atoms. However, the Nosé-Hoover thermostat fails to maintain the system temperature at a constant value during the compression process. Thus, this study indicates that the Langevin and velocity rescaling thermostats are more appropriate for use in classical MD simulations of CNT systems than the Nosé-Hoover thermostat, and reveals the conditions under which these thermostats should be used for optimal consistency.