  We investigate the electronic structure of the c(4 x 2) reconstructed Ge(001)
surface using band structure calculations based on density functional theory
and the generalized gradient approximation. In particular, we take into account
the details of surface reconstruction by means of well relaxed crystal
structures. The surface electronic states are identified and the local density
of states is compared to recent data from scanning tunneling spectroscopy. We
obtain almost perfect agreement between theory and experiment for both the
occupied and unoccupied states, which allows us to clarify the interpretation
of the experimental data.
