  We put forward a tight-binding model for rhombohedral topological insulators
materials with the space group $D^{5}_{3d}(R\bar{3}m)$. The model describes the
bulk band structure of these materials over the whole Brillouin zone. Within
this framework, we also describe the topological nature of surface states,
characterized by a Dirac cone-like dispersion and the emergence of surface
projected bulk states near to the Dirac-point in energy. We find that the
breaking of the $R_{3}$ symmetry as one moves away from the $\Gamma$ point has
an important role in the hybridization of the $p_x$, $p_y$, and $p_z$ atomic
orbitals. In our tight-binding model, the latter leads to a band mixing matrix
element ruled by a single parameter. We show that our model gives a good
description of the strategies/mechanisms proposed in the literature to
eliminate and/or energy shift the bulk states away from the Dirac point, such
as stacking faults and the introduction of an external applied electric field.
