[Paper Review] Molecular Dynamics Simulations for Anisotropic Thermal Conductivity of Borophene

Yue Jia, Chun Li+4 more|arXiv (Cornell University)|May 31, 2017

Thermal properties of materials16 references3 citations

TL;DR

This study uses reverse nonequilibrium molecular dynamics (RNEMD) with the M{"u}ller-Plathe method to compute the thermal conductivity of borophene nanoribbons (BNR) and nanotubes (BNT), revealing strong anisotropy: zigzag-direction thermal conductivity is significantly higher than armchair-direction conductivity. The results show that thermal conductivity is insensitive to width, perimeter, and uniaxial strain, but strongly dependent on structure, with BNT exhibiting lower thermal conductivity than BNR.

ABSTRACT

The present work carries out molecular dynamics simulations to compute the thermal conductivity of the borophene nanoribbon and the borophene nanotube using the Muller-Plathe approach. We investigate the thermal conductivity of the armchair and zigzag borophenes, and show the strong anisotropic thermal conductivity property of borophene. We compare the results of the borophene nanoribbon and the borophene nanotube, and find the thermal conductivity of the borophene is structure dependent.

Motivation & Objective

• To investigate the anisotropic thermal conductivity of borophene using molecular dynamics simulations.
• To compare thermal transport properties between borophene nanoribbons (BNR) and nanotubes (BNT).
• To examine the influence of structural parameters such as width, perimeter, and applied strain on thermal conductivity.
• To determine whether borophene's thermal conductivity is structure-dependent and strain-insensitive.

Proposed method

• Employed the Stillinger-Weber (SW) potential to model boron-boron interactions in borophene.
• Applied the reverse nonequilibrium molecular dynamics (RNEMD) method via the M{"u}ller-Plathe algorithm to compute thermal conductivity.
• Used NVE ensemble with velocity swapping every 5 fs to establish a steady heat flux.
• Divided the system into 50 slabs along the heat flux direction to calculate temperature gradients.
• Collected temperature data every 0.5 fs over 8 million steps, with equilibration of 300,000 steps.
• Simulated both armchair and zigzag BNR and BNT with varying widths, perimeters, and applied strains.

Experimental results

Research questions

• RQ1 What is the thermal conductivity of borophene nanoribbons in the armchair and zigzag directions?
• RQ2 How does the thermal conductivity of borophene nanotubes compare to that of nanoribbons?
• RQ3 Does the thermal conductivity of borophene depend on its width or perimeter?
• RQ4 How does uniaxial strain along the heat flux direction affect thermal conductivity?
• RQ5 Is the thermal conductivity of borophene anisotropic, and if so, how strong is the anisotropy?

Key findings

• The thermal conductivity of zigzag-direction borophene nanoribbons reaches 408.03 W/mK, significantly higher than the 174.86 W/mK in the armchair direction.
• Thermal conductivity of borophene nanoribbons is independent of ribbon width, with values remaining stable across different widths.
• Thermal conductivity of borophene nanotubes is insensitive to changes in perimeter, maintaining consistent values across different perimeters.
• The thermal conductivity of both borophene nanoribbons and nanotubes is unaffected by uniaxial strain up to 2% along the heat flux direction.
• Borophene nanotubes exhibit lower thermal conductivity than nanoribbons, indicating a strong structure dependence of thermal transport.
• The study confirms strong intrinsic thermal anisotropy in borophene, with the zigzag direction showing significantly higher thermal conductivity than the armchair direction.