  The passivation of thin Bi(1 1 1) films with hydrogen and oxide capping
layers is investigated from first principles. Considering termination related
changes of the crystal structure, we show how the bands and density of states
are affected. In the context of the much discussed semimetal-to-semiconductor
transition and the band topology of the bulk material, we consider the effects
of confinement in the whole Brillouin zone and go beyond standard density
functional theory by including many-body interactions via the G$_0$W$_0$
approximation. The conductivity of unterminated films is calculated via the
Boltzmann transport equation using the simple constant relaxation time
approximation and compared to experimental observations which have suggested a
two-channel model.
