  A multiband empirical tight-binding model for group-III-nitride
semiconductors with a wurtzite structure has been developed and applied to both
bulk systems and embedded quantum dots. As a minimal basis set we assume one
s-orbital and three p-orbitals, localized in the unit cell of the hexagonal
Bravais lattice, from which one conduction band and three valence bands are
formed. Non-vanishing matrix elements up to second nearest neighbors are taken
into account. These matrix elements are determined so that the resulting
tight-binding band structure reproduces the known Gamma-point parameters, which
are also used in recent kp-treatments. Furthermore, the tight-binding band
structure can also be fitted to the band energies at other special symmetry
points of the Brillouin zone boundary, known from experiment or from
first-principle calculations. In this paper, we describe details of the
parametrization and present the resulting tight-binding band structures of bulk
GaN, AlN, and InN with a wurtzite structure. As a first application to
nanostructures, we present results for the single-particle electronic
properties of lens-shaped InN quantum dots embedded in a GaN matrix.
