  Possibility for the formation of stable Al atomic wire on the Si(211) surface
is investigated using density functional theory based total energy
calculations. The stable adsorption sites and the surface structures at various
sub-monolayer coverages of Al are presented. It is found that the most stable
and natural surface structures around one monolayer coverage is either
$1\times5$ or $1\times6$ which agrees with experimental observations. More
significantly, our study revealed that unlike the case of Ga the formation of
continuous atomic Al chains assisted by interrupted Al chains may be possible
by controlling the experimental conditions (pressure and temperature) such that
the $\mu_{\rm Al}$ remains within $\sim 0.3$ eV from the bulk value. While the
Al covered Si(211) surface may be metallic or semiconducting, the Ga covered
Si(211) is always semiconducting in nature below 1 ML coverage. Also
significant is the fact that Al atoms move from groove sites to the sites
between terrace and trench atoms through lower energy channels as the coverage
goes from 1/8 monolayer to 1/4 monolayer.
