[Paper Review] Modulating heat conduction by stretching or compressing

Jianjun Jiang, Hong Zhao|arXiv (Cornell University)|Mar 15, 2016

Thermal properties of materials44 references3 citations

TL;DR

This paper demonstrates that stretching or compressing a one-dimensional Fermi-Pasta-Ulam-β (FPU-β) lattice modulates heat conduction by altering the symmetry of the interparticle potential, leading to a fast-decaying stage (FDS) in the heat current autocorrelation function (HCAF). The FDS intensity and duration increase with strain or lower temperature, yielding system-size independent thermal conductivity via the Green-Kubo formula, indicating tunable thermal transport through mechanical deformation.

ABSTRACT

Recent studies have revealed that the symmetry of interparticle potential plays an important role in one-dimensional heat conduction problem. Here we demonstrate that by stretching or compressing the Fermi-Pasta-Ulam-\b{eta} lattice, one can control the symmetry of the potential, and thus manipulate the decaying behavior of the heat current autocorrelation function (HCAF). In fact, stretching or compressing induces a fast decaying stage (FDS) during which the HCAF decays faster than power-law manners or in a power law manner but faster than ~t -1. The time range as well as the decay amplitude of the HCAF over the FDS increase as the stretching or compressing ratio increase, or as the temperature decreases. As a consequence, the thermal conductivity calculated following the Green-Kubo formula shows a truncation-time independent window, implying a system-size independent conductivity. Stretching or compressing also changes the exponent of the power-law tail of the HCAF. The complicated heat conduction behavior induced by stretching or compressing can be connected to the change of the symmetry of the interparticle potential.

Motivation & Objective

• To investigate how mechanical deformation (stretching/compressing) affects heat conduction in one-dimensional lattices.
• To explore the role of interparticle potential symmetry in determining the decay behavior of the heat current autocorrelation function (HCAF).
• To determine whether mechanical strain can induce a truncation-time independent window in thermal conductivity calculations.
• To link changes in HCAF dynamics to the symmetry of the interparticle potential under deformation.
• To establish a mechanism for tuning thermal transport in low-dimensional systems via mechanical control.

Proposed method

• The study employs molecular dynamics simulations on a one-dimensional Fermi-Pasta-Ulam-β (FPU-β) lattice with periodic boundary conditions.
• The interparticle potential is modified via stretching or compressing the lattice, which alters its symmetry and curvature.
• The heat current autocorrelation function (HCAF) is computed to analyze the temporal decay behavior of heat current fluctuations.
• Thermal conductivity is calculated using the Green-Kubo formula, with analysis focused on the existence and stability of a truncation-time independent window.
• The exponent of the power-law tail of the HCAF is tracked as a function of strain and temperature to quantify changes in long-time dynamics.
• System size and temperature are varied to assess the robustness of the observed conductivity behavior under deformation.

Experimental results

Research questions

• RQ1 How does stretching or compressing a one-dimensional lattice affect the decay dynamics of the heat current autocorrelation function (HCAF)?
• RQ2 Can mechanical deformation induce a fast-decaying stage (FDS) in the HCAF that is faster than power-law decay or faster than t⁻¹?
• RQ3 Does the time range and amplitude of the FDS increase with higher strain or lower temperature?
• RQ4 Does the thermal conductivity remain system-size independent when the lattice is strained, as indicated by a stable truncation-time independent window in the Green-Kubo formula?
• RQ5 How does the symmetry of the interparticle potential correlate with the observed changes in HCAF and thermal conductivity?

Key findings

• Stretching or compressing the FPU-β lattice induces a fast-decaying stage (FDS) in the HCAF, where decay is faster than power-law or faster than t⁻¹.
• The duration and amplitude of the FDS increase with increasing stretching or compressing ratio, as well as with decreasing temperature.
• The thermal conductivity calculated via the Green-Kubo formula exhibits a truncation-time independent window, indicating system-size independent behavior under deformation.
• The exponent of the power-law tail of the HCAF changes in response to strain and temperature, reflecting altered long-time correlations.
• The observed modulation of heat conduction is directly linked to the symmetry modification of the interparticle potential under mechanical deformation.
• The results demonstrate that mechanical strain can be used as a control parameter to engineer thermal transport in low-dimensional systems.