Surface properties of alkaline earth metal oxides

Structural and energetic surface properties of the alkaline earth metal oxides MgO, CaO, SrO, and BaO are investigated within the density functional theory. In particular, structural distortions (relaxation and rumpling) and surface energies are studied for the (1 0 0) and (1 1 0) surfaces. A different sign of the rumpling is calculated for MgO compared to the other oxides. This difference is carefully examined and discussed in terms of differences in electronic properties, as well as nearest and next-nearest neighbor interactions. The stability of the results is investigated with respect to model approximations, such as the finite number of atomic layers used to describe semi-infinite surfaces, and choice of exchange-correlation energy functional.