Effects of Coulomb interactions in electron transport through short molecular chains
Wybrane pełne teksty z tego czasopisma
Charge transport properties of short molecular chains connected to electrodes are studied using the non-equilibrium Green function method. The chains are described using a single-orbital Hubbard model. In the weak interaction range and low-temperature limit, the current flowing through the system was analysed within the Hartree-Fock approximation (HFA). It was found that for a weak coupling between the molecule and the leads I-V characteristics can be represented as a sequence of plateaus, alternating with regions of a finite slope. This finite slope in the I-V characteristics is related to the self-consistent molecular level being pinned down to the Fermi levels of the electrodes over a finite voltage regions. It is also related to a continuous change in the charge state of the molecule. In the strong repulsion limit, the HFA method is no longer credible and we resort to decoupling the equations of motion (EOM) for the Green functions of the chains, in order to treat all intrachain correlations and hopping exactly but to neglect some correlations between the molecule and the leads. A comparison of the results obtained with these two approaches for the same parameters allows us to make general observations concerning the role of correlations in transport through molecular junctions.
Bibliogr. 37 poz.