Molecular Dynamics

Abstract

The aim in this Chapter is to show how molecular dynamics can be used to study conductive heat transfer in matter in terms of an atomic description of that matter. Molecular dynamics can only be used to study heat transfer by phonons, i.e., vibrations of the atomic lattice. It therefore only applies to dielectric materials, i.e., electrical insulators and semiconductors, in which the concentration of free electrons in the lattice is low enough to ensure that heat transfer by electrons is negligible compared with heat transfer by phonons.

There will be two applications here:

• Prediction of the thermal conductivity of macroscopic materials on the basis of a description of their atomic structure: crystals, amorphous materials, with and without defects (voids, substitution defects, interstitial defects, dislocations, and grain boundaries), multilayer composite materials, superlattices, and so on.

• Prediction of the thermal conductivity of nanostructures: nanoparticles, nanowires, nanofilms, nanotubes, and so on.

Since molecular dynamics is not widely used in the heat transfer community, the first part of this Chapter presents the basic principles and implementation of the technique. Section 2 discusses the methods most widely used to calculate the thermal conductivity with the help of molecular dynamics simulations. The thermal conductivity can be calculated on the basis of behavioural models. We shall see in Sect. 3 that molecular dynamics can be used as a tool for determining the vibrational properties of the materials required in these models.