Grotthuss-type oxygen hole polaron transport in desodiated NaMnO
arXiv:2504.02054 · doi:10.1103/bd8s-74zt
Abstract
Polarons are quasiparticles that arise from the coupling of electrons or holes with ionic vibrations in polarizable materials. Typically, they are either localized at a single atomic site or delocalized over multiple sites. However, after the desodiation of NaMnO, we identify a rare split-hole polaron, where a single hole is shared between two adjacent oxygen atoms rather than fully localized or delocalized. We present a density functional theory (DFT) study on the migration and transport properties of these oxygen hole polarons in NaMnO and NaMnO. Our calculations reveal that the split polaron configuration near a sodium vacancy is the ground state, while the localized polaron acts as the transition state. Migration occurs via a stepwise charge transfer mechanism along the -axis, where the split-hole polaron transitions through a localized hole state. This transport behavior closely resembles the Grotthuss mechanism, which describes proton transport in HO. We compute the polaron mobility as = 1.37 10 cm/(Vs) with an energy barrier of 242 meV. Using the Mulliken-Hush theory, we determine the electronic coupling parameter = 0.87 eV. A similar migration mechanism is observed in NaMnO, where the split polaron remains more stable than in the localized state. This study provides the first theoretical investigation of split-hole polaron migration, offering new insights into the charge transport of exotic polaronic species in materials with implications for a wide range of functional materials including battery cathodes, thermoelectrics, photocatalysts, and next-generation optoelectronic devices.