Obtaining the Phonon Mean Free Paths of Inhomogeneous Materials using Molecular Dynamics Dislocation Core

Thermal management is extremely important for designing high-performance devices. The lattice thermal conductivity of materials is strongly dependent on the detailed structural defects at different length scales, particularly point defects like vacancies, line defects like dislocations, and planar defects such as grain boundaries. To evaluate the phonon mean free paths (MFPs), the McKelvey-Shockley phonon Boltzmann's transport equation (BTE) method combined with molecular dynamics simulations has been widely used. However, this method can only provide the aggregate MFPs of the whole sample, it is challenging to extract the MFPs in different regions with various thermal conductivities. In this study, the 1D McKelvey-Shockley phonon BTE method was extended to model thermally inhomogeneous materials, where the contributions of defects to the phonon MFP can be obtained. Then, the method was used to study the phonon scattering with the core structure of edge dislocation. The phonon MFPs in the dislocation core were obtained and consistent with the analytical model in a way that high frequency phonons are likely to be scattered in this area. This method not only advances the knowledge of phonon dislocation scattering but also shows the potential to investigate materials with more complicated components with different phonon behaviors.