Nonequilibrium Generalised Langevin Equation for the calculation of heat transport properties in model 1D atomic chains coupled to two 3D thermal baths

TL;DR

This paper employs a Generalised Langevin Equation approach to analyze heat transport in 1D atomic chains coupled to 3D thermal baths, revealing diffusive and ballistic regimes depending on temperature and chain length.

Contribution

It introduces a GLE-based method to study thermal transport in model atomic chains connected to realistic 3D baths, capturing both linear and nonlinear regimes.

Findings

High-temperature chains exhibit diffusive transport with temperature gradients.

Low-temperature chains show ballistic-like transport behavior.

Transport regimes depend on chain length and temperature differences.

Abstract

We use a Generalised Langevin Equation (GLE) scheme to study the thermal transport of low dimensional systems. In this approach, the central classical region is connected to two realistic thermal baths kept at two different temperatures [H. Ness et al., Phys. Rev. B {\bf 93}, 174303 (2016)]. We consider model Al systems, i.e. one-dimensional atomic chains connected to three-dimensional baths. The thermal transport properties are studied as a function of the chain length $N$ and the temperature difference $\Delta T$ between the baths. We calculate the transport properties both in the linear response regime and in the non-linear regime. Two different laws are obtained for the linear conductance versus the length of the chains. For large temperatures ($T \gtrsim 500$ K) and temperature differences ($\Delta T \gtrsim 500$ K), the chains, with $N > 18$ atoms, present a diffusive transport regime with the presence of a temperature gradient across the system. For lower temperatures($T \lesssim 500$ K) and temperature differences ($\Delta T \lesssim 400$ K), a regime similar to the ballistic regime is observed. Such a ballistic-like regime is also obtained for shorter chains ($N \le 15 $). Our detailed analysis suggests that the behaviour at higher temperatures and temperature differences is mainly due to anharmonic effects within the long chains.