Ab initio insight into the formation of small polarons: A study across four metal peroxides
Abstract
In this ab initio study, we investigate the initial stages of small polaron formation across four metal peroxides. By separating out electronic and lattice energy contributions to the formation of electron polarons, we find both large and small formation barriers directly correlated with an electronic relaxation delay. Further analysis of the electronic structure evolution during polaron formation, within the constraints set by the generalized form of Koopmans’ theorem, reveals that hybridization between the polaron anchoring orbital and the conduction band minimum determines the electronic relaxation delay. This hybridization physics is shown to play a dominant role in the magnitude of a polaron formation barrier and the adiabaticity of polaron charge localization. Weaker hybridization is correlated with larger more diabatic formation barriers, while stronger hybridization is correlated with smaller more adiabatic formation barriers. These ab initio insights may lead to new approaches towards tailoring the formation of small polarons in energy and electronic materials.
