  First-principles calculations using density functional theory based on
norm-conserving pseudopotentials have been performed to investigate the Mg
adsorption on the Si(001) surface for 1/4, 1/2 and 1 monolayer coverages. For
both 1/4 and 1/2 ML coverages it has been found that the most favorable site
for the Mg adsorption is the cave site between two dimer rows consistent with
the recent experiments. For the 1 ML coverage we have found that the most
preferable configuration is when both Mg atoms on 2x1 reconstruction occupy the
two shallow sites. We have found that the minimum energy configurations for 1/4
ML coverage is a 2x2 reconstruction while for the 1/2 and 1 ML coverages they
are 2x1.

Soft Condensed Matter;Materials Science