  Non-equilibrium Greens function techniques (NEGF) combined with Density
Functional Theory (DFT) calculations have become a standard tool for the
description of electron transport through single molecule nano-junctions in the
coherent tunneling regime. However, the applicability of these methods for
transport in the Coulomb blockade (CB) regime is still under debate. We present
here NEGF-DFT calculations performed on simple model systems in the presence of
an effective gate potential. The results show that: i) the CB addition energies
can be predicted with such an approach with reasonable accuracy; ii) neither
the magnitude of the Kohn-Sham gap nor the lack of a derivative discontinuity
in the exchange-correlation functional represent a problem for this purpose.
