Optimizing interatomic potentials for phonon properties
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Molecular dynamics (MD) simulations calculate the trajectory of atoms as a function of time. Material properties that depend on the dynamics of atoms can be predicted in terms of these atomic motions, yielding insight into atomic-level behaviors that ultimately dictate these properties. Such insight is crucial for developing a low-level understanding of material behavior, and MD simulations have been used to successfully predict properties for decades. Thermal transport properties in solids are largely dictated by collective atomic vibrations known as phonons, which can be understood and probed deeply through analysis of MD trajectories. The heart of MD simulations is the mathematical representation of potential energy between atoms, termed the interatomic potential, from which the forces and dynamics are calculated. The use of MD simulations to generally predict and describe thermal transport has not been fully realized due to the lack of accurate interatomic potentials for a variety of systems and obtaining accurate interatomic potentials is not a trivial task. Furthermore, it is not known how to create potentials that are guaranteed to accurately predict phonon properties, and this thesis seeks to answer this question. The goal is to create potentials that accurately predict phonon properties, which are thereby termed phonon optimized potentials (POPs).