AB initio hartree-fock study of the MgO(001) surface

The MgO(001) surface has been studied with an ab initio Hartree-Fock crystalline orbital LCAO program. An optimized basis set containing nine atomic orbitals (three s and six p) per atom has been used. The semi-infinite crystal has been simulated by a slab containing three planes (six atoms per cell). In agreement with the most recent LEED experiments, no relaxation is found and the “rumpling” is very small (1% of the nearest neighbour separation in the bulk). The analysis of the electron charge distribution and of the ion multipoles shows that the fully ionic character found for the bulk is maintained at the surface, and that the anion deformation is very small. A surface energy of 1.43 J/m 2 was obtained.