Abstract: The adsorption of a half monolayer of Mg atoms on the Si (100)-(2 × 1) surface is studied by using the self-consistent tight binding linear muffin-tin orbital method. Energies of the adsorption systems of Mg atoms on the different sites are calculated. It has been found that the adsorbed Mg atoms are more favorable on the cave site above the surface than any other sites on the Si (100)-(2 × 1) surface and a metastable shallow site also exists above the surface. This is in agreement with the experimental results. The charge transfer and the layer projected density of states are also studied.

Key words: silicon, chemisorption, supercell, magnesium, low index single crystal surface