Classical to quantum transition of near-field heat transfer between two nanoparticles

TL;DR

This paper explores the transition from classical to quantum heat transfer mechanisms between nanoparticles as their separation distance varies from a few angstroms to nanometers, revealing a shift from surface charge interactions to quantum electron sharing.

Contribution

It provides a detailed analysis of the distance-dependent transition from classical to quantum heat transfer between nanoparticles using the non-equilibrium Green's function method.

Findings

Thermal conductance decreases with distance initially, then increases dramatically at very small gaps.

Surface charge-charge interactions dominate at intermediate distances.

Quantum electron sharing occurs at gaps smaller than 4 Å, significantly enhancing heat transfer.

Abstract

Heat transfer between two silica clusters is investigated by using the non-equilibrium Green's function method. In the gap range between 4 {\AA} and three times the cluster size, the thermal conductance decreases as predicted by the surface charge-charge interaction. Above five times the cluster size, the volume dipole-dipole interaction predominates. Finally, when the distance becomes smaller than 4 {\AA}, a quantum interaction where the electrons of both clusters are shared takes place. This quantum interaction leads to the dramatic increase of the thermal coupling between neighbor clusters due to strong interactions. This study finally provides a description of the transition between radiation and heat conduction in gaps smaller than a few nanometers.