Kinetic control of the current through a single molecule

A unified description is put forward for the electron transmission through a molecule that is attached to two leads with the molecule being characterized by a single level to be populated by the transferred electrons. In deriving the expression for the current the Coulomb interaction is accounted for between the two extra electrons that may occupy the molecular level. The formation of two distinct transmission channels associated with the neutral and the singly charged molecule can directly be related to this interaction. Moreover, each transmission channel comprises a sequential as well as a direct (tunneling) pathway. The first pathway is realized via hopping transitions between the molecule and the neighboring electrodes. Just this inelastic kinetic process is responsible for the kinetic charging of the molecule. Then, the second pathway takes place against the background of kinetic molecular charging. In particular, it is demonstrated that hopping transmissions which are asymmetric with respect to the two electrodes cause a kinetic current rectification. The transient population of the molecule, realized by the transferred electrons, determines the rectification; the latter becomes rather large for resonant transmission. 2006 Elsevier B.V. All rights reserved.