A general formalism is developed for the theory of electronic current through a molecule attached to macroscopic electrodes in a given bias. The current is calculated in a non-perturbative many-body formalism. We obtain an intuitively appealing formula. We identify two distinct limits: the Kubo linear response formula valid in the small bias regime and the Landauer formula valid for non-interacting electrons. Finally, we develop a new correlation function formula, which is more amenable to numerical computations and discuss the application of absorbing potentials in the electrodes as a possible means of calculation.
Bibliographical noteFunding Information:
We thank M. Ratner, E. Rabani and R. Kosloff for useful discussions. This work was supported by the Israel Science Foundation founded by the Israel Academy of Sciences and Humanities, the USA National Science Foundation and the Petroleum Research Fund.