The electronic structure and phase diagram of chlorine adsorption on Mg (0 0 0 1) surface

First-principles methods are applied to investigate the adsorption energy and electronic structure of p(2 × 2) configuration of chlorine atoms adsorbed in variety of sites of Mg (0 0 0 1) surface. It is found that the fcc-hollow site is the energetically most favorable for the whole coverage range considered. The adsorption energy decreases with the increasing coverage θ. It can be concluded from the charge densities and density of states that the charges transfer between substrate Mg atoms and Cl atoms leads to the appearance of dipole moment. It has been also found from the electronic structure that the repulsion between Cl atoms becomes stronger and the charge distribution is localized getting closer to the Cl atoms with the increasing coverage. The chlorine adatom reduces the surface energy rapidly and leads to form the stable bulk MgCl2 and in the fcc-hollow site adsorption the 1/4 ML Cl–Mg structure is stable while the higher 1/2 ML, 3/4ML and 1/1ML Cl–Mg structures are unstable from the phase diagram of Cl–Mg structures.