  By using first-principles plane wave calculations, we systematically study
the electronic properties of the thin film of antimony in (111) orientation.
Considering the spin-orbit interaction, for stoichiometric surface, the
topological states keep robust for six bilayers, and can be recovered in the
three bilayer film, which are guarantied by time-reversal symmetry and inverse
symmetry. For reduced surface doped by Bi or Mn atom, localized 3-fold
symmetric features can be identified. Moreover, the non-trivial topological
states stand for non-magnetic substituted Bi atom, while can be eliminated by
adsorbed or substituted magnetic Mn atom.
