First-principles characterization of single-electron polaron in WO3

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 singlepolaron in WO3 from density functional theory calculations. Our calculations show that the single polaron is at ahigher energy than the fully delocalized solution, in agreement with the experiments where a single polaron is anexcited state of WO3. The symmetry-adapted mode decomposition of the polaron distortions shows that, amongnumerous modes, a polar zone center mode has the largest contribution and can be at the origin of the observedweak ferroelectricity of WO3.