Water adsorption and dissociation on the PuO2(1Â 1Â 0) surface

Adsorption of the H2O molecule on the PuO2(1 1 0) surface is studied by density-functional calculations. The strong electronic correlations in the PuO2 compound are treated in the DFT+U (Hubbard) formalism. A dissociated state of water is identified, resulting in the formation of hydroxyl groups and corresponding to a very exothermic process. However, a non-dissociated (molecular) form does exist as a metastable state. The Infra-Red and XPS signature of both forms are identified and compared to experiments. Kinetic Monte Carlo simulations show that adsorbed molecular water might have a long life-time before dissociating at low temperature, due to a small energy barrier between the molecular and dissociated configurations, in agreement with experiments.