Toda lattice formed in nonequilibrium steady states of SWCNT

Abstract

Toda lattice or FPUT chain-like dynamics have been regarded as the prerequisite condition to explain the length dependency of high thermal conductivity of low-dimensional systems at the nanoscale. In this paper, a hypothetical condition is introduced that establishes a theoretical connection between the thermal conductivity of a nanoscale low-dimensional system in nonequilibrium steady states(NESS) and the canonical motion of the equation in the Toda lattice in equilibrium. The hypothesis relies on a numerically driven coarse grained molecular dynamics(CGMD) system acquired from the trajectory data of nonequilibrium molecular dynamics(NEMD) simulation. It models the macroscopic motion from longitudinal and flexural modulation observed in NEMD as a separate Hamiltonian in CGMD with a perturbation term governed by an overdamping process, which is assumed to be dominant during heat transfer. The Smoluchowski equation for the perturbation, which is derived from the cross correlated states between two degrees of freedom, suggests that the potential energy function induced from NESS is identical to that of the Toda Lattice under the specific condition in the partition function for coarse grained particles. The restrictions derived from the model are well confirmed by the data from the numerically driven coarse grained model.