Heat diffusion related damping process in highly precise coarse-grained model for SWCNT's nonlinearity

TL;DR

This paper introduces a heat diffusion-based damping process in a coarse-grained model for SWCNTs, improving the simulation of their nonlinear dynamics by incorporating internal heat diffusion effects without external thermostats.

Contribution

It develops a novel coarse-grained molecular dynamics model that explicitly includes internal heat diffusion to accurately replicate SWCNT nonlinearity.

Findings

The model reproduces nonlinear SWCNT motion without external thermostats.

Heat diffusion causes synchronization between CGMD and MD simulations.

The approach captures dispersive wave characteristics in SWCNTs.

Abstract

Second sound and heat diffusion in single-walled carbon nanotubes (SWCNT) is well-known phenomena which is related to the high thermal conductivity of this material. In this paper, we have shown that the heat diffusion along the tube axis affects the macroscopic motion of SWCNT and adapting this phenomena to coarse-grained model can improve the precision of the coarse-grained molecular dynamics (CGMD) exceptionally. The nonlinear macroscopic motion of SWCNT in the free thermal vibration condition in adiabatic environment is demonstrated in the most simplified version of CG modeling as maintaining finite temperature and total energy with suggested dissipation process derived from internal heat diffusion. The internal heat diffusion related to the cross correlated momentum from different potential energy functions is considered, and it can reproduce the nonlinear dynamic nature of SWCNTs without external thermostatting in CG model. Memory effect and thermostat with random noise distribution are not included, and the effect of heat diffusion on memory effect is reviewed through Mori-Zwanzig formalism. This diffusion shows perfect syncronization of the motion between that of CGMD and MD simulation, which is started with initial conditions from the molecular dynamics (MD) simulation. The heat diffusion related to this process has shown the same dispersive characteristics to second wave in SWCNT. This replication with good precision indicates that the internal heat diffusion process is the essential cause of the nonlinearity of the tube. The nonlinear dynamic characteristics from the various scale of simple beads systems are examined with expanding its time step and node length simultaneously.