Heat Flow in Heterostructures

Existing theoretical descriptions of thermal transport through heterostructures describe the process in terms of empirical reflection and transmission. First-principles theoretical tools are required to describe at the atomic level the flow of heat at the boundary between two materials. The interactions between the (localized) phonons associated with the interface and the (delocalized) bulk phonons can be described using ab-initio molecular-dynamics simulations provided that temperature fluctuations are controlled without using a thermostat. This can be achieved by preparing the supercell using the eigenvectors of the dynamical matrix. Our approach and preliminary results dealing with a Ge layer in a Si nanowire will be discussed.