Molecular and atomic oxygen diffusion on uranium mononitride UN(001) surface was studied. The more
favorable bridge site corresponding to the oxygen diffusion on UN(001) clean surface was then checked under several
surface states such as UN(001) surfaces including uranium or nitrogen vacancies. First principle calculation based on
density functional theory (DFT) was used with the generalized gradient approximation (GGA) to describe the exchangecorrelation
and the projector-augmented wave (PAW) as pseudo potential. Molecular and atomic potential energy surfaces
(PES) corresponding to the interaction between respective molecular (O2) or atomic oxygen (O) and UN(001) surface
states at several positions of the surface were used to study and identify the more favorable adsorption sites. The
dissociation of molecular oxygen approaching UN(001) surfaces both clean or defected was proved for different
orientation of the molecule with both atoms adsorbed on the surfaces. The more ability of oxygen adsorption on UN(001)
nitrogen vacancy surface compared to other UN(001) surfaces states was confirmed. Considering more N vacancies on
UN(001) surface and more O atoms diffusion, our results show that adsorption energies per O atom decrease with the rise
in N vacancies and increase with increasing O atoms diffusion.
Keywords: Abinitio, DFT, GGA, N vacancy, PES, Uranium monoNitride UN, U vacancy.
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