Nonlinear Coherent Transport Through Doped Nanotube Junctions

0l Vpa y i ai0 , (1) where the sum over lattice sites i and i 0 is restricted to nearest neighbors. We consider one p orbital per atom and set the value of the hopping integral equal to 1. (Experiments [6] show good agreement with theoretical results for Vp › 2.7 6 0.1 eV.) Henceforth, the unit of energy is chosen to be the hopping integral, unless otherwise specified. The Hubbard term UHdni is added for the self-consistent treatment of charge transfer at the junction, and dni is the change in the occupation number at site i, compared to that of the bulk crystal. The self-consistent treatment is needed in order to obtain the exact form of the potential drop at the junction, especially when a large external potential difference is applied to the two sides of the system. We use the experimental value of the Hubbard