CAREER: Coupling Between Correlated Electrons and Phonons from First Principles

About This Grant

NONTECHNICAL SUMMARY This award supports research, education, and outreach activities focused on understanding materials properties driven by the coupling between electrons and the vibrations of atom lattices in solids. This electron-lattice vibration interaction is fundamental to many phenomena, such as electric heating in transistors, light absorption and energy conversion in solar cells, and superconductivity where electric current is conducted with zero loss. The theoretical understanding of these phenomena can be simplified by considering electrons as independent of each other and considering their coupling to the lattice vibrations individually. However, in many topical materials of technological significance, electrons interact strongly among themselves while also collectively coupled to the lattice vibrations. Such strong interaction and coupling leads to exotic quantum phenomena, but it also presents challenges in achieving a clear understanding of the behaviors of such materials. This project addresses these challenges by developing and applying advanced quantum-mechanical computational approaches and large-scale simulation techniques. The goal of this research is to reveal the actual role of electron-lattice vibration coupling in interacting-electron materials systems and to explain intricate phenomena observed in novel superconductors and semiconductors. This project supports the education of a graduate student. Additionally, the project integrates research, community building, education, and outreach activities, by targeting a wide range of researchers, from high-school students to undergraduate students, to graduate students, and postdoctoral researchers. The PI will provide summer internship positions for high-school and undergraduate students and design appropriate research training projects. This project will also support various tutorial workshops to promote advanced computational methods for the young generations and foster collaborations in the scientific community. TECHNICAL SUMMARY This award supports research, education, and outreach activities focused on studying the interaction between phonons and many-body correlated electrons, and the role of electron-phonon coupling in driving exotic phases in and out of equilibrium. The understanding remains elusive largely due to the lack of appropriate ab initio methodologies that treat electron-electron and electron-phonon interactions at the many-body level simultaneously. This project will use newly developed many-body approaches, namely GW perturbation theory and time-dependent adiabatic GW with phonons (where G represents the single-particle Green function and W is the screened Coulomb interaction), to (i) address the role of phonons in unconventional and novel superconductors, and (ii) investigate many-body self-energy effects and nonequilibrium dynamics in phonon-assisted optical phenomena in semiconductors. This project will push forward the ab initio electron-phonon coupling computation into the many-electron level and the nonequilibrium regime, vastly expanding the application scope of many-body perturbation theory to phonon-relevant phenomena. This project integrates research, community building, education, and outreach activities to expose a broad range of generations of students and researchers to various computational and theoretical techniques and scientific advancements. This project will promote novel electron-phonon coupling computational approaches through pilot workshops and foster coherent collaborations among software developers and users. The PI will provide summer internship positions for high-school and undergraduate students via designed outreach and education activities to introduce frontier materials and physics research progress, and to prepare young generations to pursue future careers in science and engineering. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.