content_image/336362.jpg
<img src='content_image/336362.jpg'>

So far, we have considered the dependence on the location of molecular level α relative to the electrode Fermi energy. We also employed this renormalization scheme to study the J - and ξ -dependence of the linear conductance away from resonance α ̸ = ε$_{F}$ . (Remember that G |$_{α}$ = ε$_{F}$ = G 0 for all ξ ’s and J ’s.) Results of this kind are depicted in Fig. 5, which includes both unrenormalized and normalized curves (thin and thick lines, respectively). They confirm that the size-dependence is stronger at larger ξ ’s, as already mentioned above. In addition, they reveal the interesting fact that the dependence of the Coulomb contact interaction J can be non-monotonic, as is the case of other previously published results [37]. As a general trend, we found that by increasing J the conductance G ( J ) gradually increases from the value G |$_{J}$ =0 , reaching its maximum at a Coulomb strength J$_{c}$ ∼ ξ , and decreases afterwards. This trend can be seen by inspecting Fig. 5, which also shows that the wider the electrode bandwidth (4 ξ ), the more pronounced is the conductance enhancement G ( J$_{c}$ ) /G ( J = 0). 

## VII. DISCUSSION 

Within the NEGF-DFT approaches, the impact of electron correlations on the Green’s function of the isolated extended molecule is accounted for approximately, ˆ G$_{i}$ |$_{DF T}$ ≈ ˆ G$_{i}$ , by employing certain exchange-correlation (xc-)functionals. To determine the Green’s function 

