Screening effects in a density functional theory based description of molecular junctions in the Coulomb blockade regime

We recently introduced a method based on density functional theory and a nonequilibrium Green's function technique for calculating the addition energies of single-molecule nanojunctions in the Coulomb blockade regime. Here we apply this approach to benzene molecules lying parallel and at various distances from two aluminum fcc (111) surfaces, and we discuss the distance dependence in our calculations in terms of electrostatic screening effects. The addition energies near the surface are reduced by about a factor of 2, which is comparable to previously reported calculations employing a computationally far more demanding quasiparticle description.