O2, CO2, and H2O Chemisorption on UN（001） Surface： Density Functional Theory Study

O2、CO2和H2O在UN（001）表面化学吸附的密度泛函理论研究

We performed density functional theory calculations of O2, CO2, and H2O chemisorption on the UN（001） surface using the generalized gradient approximation and PW91 exchangecorrelation functional at non-spin polarized level with the periodic slab model. Chemisorption energies vs. molecular distance from UN（001） surface were optimized for four symmetrical chemisorption sites. The results showed that the bridge parallel, hollow parallel and bridge hydrogen-up adsorption sites were the most stable site for O2, CO2, and H2O molecular with chemisorption energies of 14.48, 4.492, and 5.85 kJ/mol, respectively. From the point of adsorbent （the UN（001） surface）, interaction of O2 with the UN（001） surface was of the maximum magnitude, then CO2 and H2O, indicating that these interactions were associated with structures of the adsorbate. O2 chemisorption caused N atoms on the surface to migrate into the bulk, however CO2 and H2O had a moderate and negligible effect on the surface, respectively. Calculated electronic density of states demonstrated the electronic charge transfer between s, p orbital in chemisorption molecular and U6d, U5f orbital.