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We study the electronic transport through interacting
molecular junctions weakly coupled to leads.
Specifically, we consider benzene and biphenyl molecules and describe them within the Pariser-Parr-Pople Hamiltonian for interacting p_z electrons. A set of generalized master equations for the reduced density matrix of the considered molecule, including coherences, is used to evaluate the system's I-V-V_gate characteristics. The interplay between interaction and orbital symmetries of the two molecules is responsible for specific fingerprints in their stability diagrams. E.g. negative differential conductance features discriminate between the meta and para configuration in the electrical contacts for benzene [1], while a peculiar gate voltage asymmetry reveals the existence of two metastable rotational configurations in the adiabatic potential of neutral biphenyl [2]. [1] G.Begemann, A.Donarini, and M.Grifoni in preparation [2] A.Donarini, M.Grifoni, and K.Richter PRL 97 166801 (2006) |
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