Atomistic Nodal Approach: a General Molecular Dynamics Method For Computing Local Thermal Conductance at Atomistic Resolution

05 October 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

The Interfacial Thermal Conductance (ITC) is a fundamental property of mate- rials and has particular relevance at the nanoscale. The ITC quanti es the thermal resistance between materials of di erent compositions or between uids in contact with materials. Furthermore, the ITC determines the rate of cooling/heating of the materi- als and the temperature drop across the interface. Here we propose a method to com- pute local ITCs and temperature drops of nanoparticle- uid interfaces. Our approach resolves the ITC at the atomic level using the atomic coordinates of the nanomaterial as nodes to compute local thermal transport properties. We obtain high-resolution descriptions of the interfacial thermal transport by combining the atomistic nodal ap- proach, computational geometry techniques and \computational farming" using Non- Equilibrium Molecular Dynamics simulations. We illustrate our method by analyzing various nanoparticles as a function of their size and geometry, targeting experimentally relevant structures like capped octagonal rods, cuboctahedrons, decahedrons, rhombic dodecahedrons, cubes, icosahedrons, truncated octahedrons, octahedrons and spheres. We show that the ITC of these very di erent geometries can be accurately described in terms of the local coordination number of the atoms in the nanoparticle surface. Nanoparticle geometries with lower surface coordination numbers feature higher ITCs, and the ITC generally increases with decreasing particle size.

Keywords

interfacial thermal conductance
Kapitza resistance
nanoscale heat transport
nanoparticles
thermoplasmonics

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Contains: computer simulation details, details on nanoparticle structures and sizes, heat transport equations, details on the numerical calculation of thermal gradients, conductance profiles for various nanoparticles, radial distribution functions nanoparticle-fluid, details on the alpha-shape method, solvent density profiles and size dependence of average coordination numbers for various nanoparticle structures
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