Non-Linear Transport through a Molecular Nanojunction
  We present a simple model of electrical transport through a metal-molecule-metal nanojunction that includes charging effects as well as aspects of the electronic structure of the molecule. The interplay of a large charging energy and an asymmetry of the metal-molecule coupling can lead to various effects in non-linear electrical transport. In particular, strong negative differential conductance is observed under certain conditions. 
Matthias H. Hettler, Herbert Schoeller and Wolfgang Wenzel