Negative differential resistance in scanning tunneling microscopy:   simulations on C$_{60}$-based molecular overlayers
  We determine the conditions in which negative differential resistance (NDR) appears in the C$_{60}$-based molecular device of [Phys. Rev. Lett. {\bf 100}, 036807 (2008)] by means of ab-initio electron-transport simulations. Our calculations grant access to bias-dependent intrinsic properties of the molecular device, such as electronic levels and their partial widths. We show that these quantities depend on the molecule-molecule and molecule-electrode interactions of the device. Hence, NDR can be tuned by modifying the bias behavior of levels and widths using both types of interactions. 
Frederico D. Novaes, Manuel Cobian, Alberto Garcia, Pablo Ordejon,   Hiromu Ueba and Nicolas Lorente
cond-mat.mes-hall cond-mat.mtrl-sci