  Electronic structure calculations are performed to obtain the As-exposed
Si(211) and the Te adsorbed As-exposed Si(211) surface. Arsenic-exposed Si(211)
may be obtained by adsorbing As on Si(211) or by replacing surface Si atoms by
As. First, we carry out systematic investigations to obtain stable As-exposed
Si(211) due to As adsorption at various coverages. We find that at 1/2
monolayer (ML) coverage of As, the highly terraced Si(211) surface becomes flat
decorated with parallel As chains extending along the [$01\bar{1}$] direction.
At 1 ML coverage the Si surface essentially retains its ideal structure with an
added layer of As. Motivated by the adsorption sequence in the HgCdTe (MCT)
growth on Si, Te adsorption on such an As-exposed Si(211) is studied and 1/2 ML
of Te coverage is found to be energetically feasible. Next, we explore a stable
As-exposed Si(211) upon replacement of surface Si atoms by As. An energetic
comparison reveals that the As-exposed Si(211) obtained by replacing surface Si
atoms with As is more favorable compared to that obtained by adsorbing As on
Si(211). In line with the adsorption sequence in the MCT growth on Si, Te is
then adsorbed on the most favorable As-exposed Si(211) and in contrast to
earlier situation, Te coverage here is found to be 1/4 of ML which agrees with
the experiment.
