SUMMARY

While thermal transport in well-ordered crystalline materials can be explained using the phonon gas model (PGM), understanding of heat transfer is more limited in disordered materials, including structurally disordered materials such as amorphous glasses and polymers. This work will develop a better understanding of thermal transport in such systems, utilizing a correlation-based approach termed the Green-Kubo formalism. We further extend this formalism to model the behavior of individual vibrational modes, termed Green-Kubo Modal Analysis (GKMA). Using this powerful new formalism, we can determine the contributions of individual vibrational modes to thermal conductivity of different materials. We apply GKMA to amorphous germanium, as well as several amorphous polymers, to better understand specific mechanisms that give rise to the comparatively small thermal conductivity in such materials. We will then use this insight to provide suggestions for how to create/structure materials with desirable (i.e. high or low) thermal conductivities.