First-principles characterization of single-electron polaron in WO3

Abstract

Polarons are physical objects of material science that are hard to capture from first-principles calculations. WO3 is a paradigmatic system to study polarons and here we present calculations of a single self-trapped single polaron in WO3 from density functional theory calculations. Our calculations show that the single polaron is at a higher energy than the fully delocalized solution, in agreement with the experiments where a single polaron is an excited state of WO3. The symmetry-adapted mode decomposition of the polaron distortions shows that, among numerous modes, a polar zone center mode has the largest contribution and can be at the origin of the observed weak ferroelectricity of WO3.