A density functional study of atomic oxygen and carbon adsorptions on (100) surface of γ-Uranium

Abstract

Oxygen and carbon adsorptions on a γ-Uranium (U) (100) surface have been studied at both non-spin-polarized (NSP) and spin-polarized (SP) levels using the generalized gradient approximation of the density functional theory (GGA-DFT) with Perdew and Wang (PW) functionals. For oxygen adsorption, the bridge position of (100) surface is found to be the most favourable site with chemisorption energy (CE) of 7.887 eV for the NSP case, and 7.965 eV for the SP case. The distances of the oxygen adatom from the U surface are found to be 1.19Å and 1.22 Å for the NSP and SP cases, respectively. The magnetic moment for this most favourable site is found to be 0.167μB per atom. For carbon adsorption, the centre position of (100) surface is found to be most favourable site with CE of 7.816 eV for the NSP case, and 7.895 eV for the SP case. The distances of the carbon adatom from the U surface are found to be 0.62 and 0.52 Å for the NSP and SP cases, respectively. The magnetic moment for this most favourable site is found to be 0.084μB per atom. The hybridization between the O 2p orbitals and U 5f orbitals is found to be rather weak but the hybridization between the C 2p orbitals and U 5f orbitals is observed to be strong.