  We report first-principles calculations that clarify atomic structures and
coverage of the metallic phases of In overlayers on Si (111) surfaces.
Calculated energy bands and scanning tunneling microscopy images along with the
obtained energetics of various phases reveal that the two metallic phases with
the $\sqrt{7} \times \sqrt{3}$ periodicity observed experimentally are single
and double In overlayers, as opposed to prevailing assignments.
