Water at α alumina surfaces : energetics dynamics and kinetics The (0001) surface of α Al₂O₃ is the most stable surface cut under UHV conditions and was studied by many groups both theoretically and experimentally. Reaction barriers computed with GGA functionals are known to be underestimated. Based on an example reaction at the (0001) surface this work seeks to improve this rate by applying a hybrid functional method and perturbation theory (LMP2) with an atomic orbital basis rather than a plane wave basis. In addition to activation barriers we calculate the stability and vibrational frequencies of water on the surface. Adsorption energies were compared to PW calculations and confirmed PBE+D2 PW stability results. Especially the vibrational frequencies with the B3LYP hybrid functional that have been calculated for the (0001) surface are in good agreement with experimental findings. Concerning the barriers and the reaction rate constant the expectations are fully met. It could be shown that recalculation of the transition state leads to an increased barrier and a decreased rate constant when ...