Jon Lafuente Bartolome, UT Austin Physics Dept.

"Ab initio theory of polarons at all couplings: from band structure renormalization to self-trapping"

Abstract: An electron propagating through a crystal may induce distortions in the lattice due to electron-phonon interactions. The emergent quasiparticle formed by the carrier and the lattice distortions is referred to as a polaron. State-of-the-art ab initio theories to describe polarons in materials currently fall into two separate categories: the weak coupling perturbative methods that describe phonon-induced band structure renormalizations, and the strong coupling adiabatic techniques that capture polaron self-trapping effects. The transition region between these regimes remains uncharted territory. In this talk I will present a self-consistent many-body theory of polarons that captures both limits and the intermediate regime within a single unified framework. The first application of the theory reveals that localization effects can have a significant impact on the band gap renormalization of insulators, carrying important implications on our current understanding of temperature-dependent band structures.