First-principle investigations of CaO (1 0 0) surface and adsorption of H2O on CaO (1 0 0)

The results of first-principles calculations about (1 0 0) surface of CaO and adsorption of water molecules on the CaO (1 0 0) have been presented. Both surface parameters (atomic structures and electronic configurations) and adsorption parameters (bond, charge and energy) of H2O on CaO (1 0 0) surface are obtained using density functional theory calculations with the generalized gradient approximation (DFT–GGA). It is found that the CaO (1 0 0) surface has large surface relaxation, which leads to surface polarization and exhibits reactivity toward the adsorption of H2O. When the coverage is 1/4 ML or 1 ML, bridge site (2B) site has been proved as the most stable site. However, as the coverage is 1/2 ML, hole site (4H) becomes the best adsorption site. In addition, the adsorption energy indicates that the interaction of H2O with CaO surface is relatively strong, so the interaction belongs to chemical adsorption.