Modeling intrinsic defects in LiNbO₃ within the Slater-Janak transition state model

Intrinsic point defects in LiNbO₃, i.e., isolated Nb antisites and Li as well Nb vacancies, are investigated from first-principles within the Slater-Janak transition state model. Thereby the electronic structure of the investigated defects is calculated with hybrid exchange-correlation functionals. This approach allows for the calculation of charge transition levels without comparing the total energies of differently charged supercells. The obtained results are in agreement with previous hybrid density-functional theory calculations based on total-energy differences. Li and Nb vacancies can be formed in the V_Li⁻ and V_Nb⁵⁻ charge states only, as long as the host is not strongly p-type or n-type, respectively. Nb_Li antisites may capture one or two electrons, forming the defect states often referred to as small bound polaron and bi-polaron