Density-functional study of water adsorption on thePuO2(110)surface

Water adsorption on a ${\mathrm{PuO}}_2\mathrm{}\left(110\right)\mathrm{}$ surface is studied using a periodic model with both the local-density approximation (LDA) and the generalized gradient approximation (GGA) of density-functional theory. The 60 core electrons of the Pu atom are represented by a relativistic effective core potential, and scalar relativistic effects have been incorporated into the valence orbitals. Both molecular and dissociative configurations of the adsorbate ${\mathrm{H}}_2\mathrm{O}$ are considered at one molecular layer coverage. For molecular water adsorption, LDA calculations indicate binding only at the top site, whereas the GGA indicates no binding for any site. Dissociative adsorption is found to be energetically more favorable than molecular adsorption, in agreement with experimental observations. The effects on the geometric and electronic structures influenced by water adsorption are investigated.