Fully relativistic density functional calculations on hydroxylated actinide oxide surfaces

The linear combinations of Gaussian-type orbitals-fitting function (LCGTO-FF) method has been used to investigate the cohesive properties of three fluorite structure actinide oxides (ThO2, UO2, and PuO2), and their clean and hydroxylated (111) surfaces, within the generalized gradient approximation (GGA) to density functional theory (DFT). Relativistic effects have been considered at both the scalar-relativistic and the fully relativistic (spin-orbit coupling included) levels of approximation. It is found here that the 5f states have only a minimal effect on the cohesive properties of these systems, despite the fact that the two heavier actinide oxides (both Mott-Hubbard-type insulators) are incorrectly predicted to be good metals. The cause of this insensitivity to the spurious metallic nature of the 5f states, is elucidated. (C) 2002 Wiley Periodicals, Inc.