Our group investigates the atomic structure and dynamics of materials, in order to reach a fundamental atomistic understanding of material behaviors and improve their practical properties. We are a multidisplinary group and collaborate with National Laboratories across the US and abroad, where we conduct many experiments and perform some of our large-scale computer simulations. Our methods provide breakthrough insights into atomistic origins of transport properties and phase transitions. We carry out sensitive experiments based on state-of-the-art neutron and x-ray scattering techniques and optical spectroscopy, and we perform advanced materials simulations based on density functional theory and molecular dynamics. For example, our extensive studies have probed atomic vibrations in crystals (phonons), and determined effects of anharmonicity and atomic-scale defects on suppressing phonon mean-free-paths to understand microscopic origins of thermal transport in a wide range of energy materials, including thermoelectrics or thermal management materials. Further, we study the coupling of phonons with electronic states and spins in metals and superconductors, in semiconductors for photovoltaics, in topological and quantum materials, in systems with metal-insulator transitions, as well as ferroelectrics and multiferroics. We have also obtained novel insights into atomic hopping processes underlying fast diffusion in so-called superionic materials for solid-state batteries.