The properties of interstitial and substitutional Li in wurtzite ZnO were modelled using hybrid density functional calculations. The impact of the band-gap error on the formation energies of the two defects and their dependence upon the Fermi level were investigated. It was found that, within a local-density approximation, the acceptor level of LiZn was very close to the valence-band top but as the band gap was opened, the acceptor state becomes more localized and the respective level was shifted upward. Taking polaronic effects into account, the ionization level of LiZn was placed between Ev+0.60eV and Ev+1.1eV. This deeper level explains the difficulty in realizing p-type ZnO using Li as monodopant. Further, the mobility of the defects was investigated. While interstitial Li was mobile at low temperatures, independent of the stoichiometry, the diffusion of LiZn depended upon the concentrations of intrinsic defects. The calculations showed that in O-rich material, where the defect was more stable, the dominant diffusion process corresponded to a dissociative mechanism requiring a substantial activation energy.A Hybrid Density Functional Study of Lithium in ZnO: Stability, Ionization Levels, and Diffusion. Carvalho, A., Alkauskas, A., Pasquarello, A., Tagantsev, A.K., Setter, N.: Physical Review B, 2009, 80[19], 195205