The surface properties of uranium dioxide

A calculation is presented of the surface energy, tension and structure of the low index faces of uranium dioxide using an ionic description of the crystal. The general properties of fluorite surfaces are discussed and detailed lattice relaxations are carried out for the (111) and (110) surfaces. The relaxed geometries show small deviations from the ideal lattice structure consisting mainly of a contraction of the (111) surface and a rumpling with lateral displacements of the (110) surface. The surface energies are sensitive to the amount of relaxation and the final values of 1069 erg cm-2 (111) and 1539 erg cm-2 (110) agree with previous estimates and experiment. The surface tensions are interpreted in terms of surface structure. (Auth.)