  Quantum transport properties of intermolecular nanotube contacts are
investigated. We find that atomic structure in the contact region plays
important roles and resistance of contacts varies strongly with geometry and
nanotube chirality. Nanotube end-end contacts have low resistance and show
negative differential resistance (NDR) behavior. Contact resistance can be
dramatically decreased by exerting small pressure/force between the tubes if
the contact is commensurate. Significant variation and nonlinearity of contact
resistance may lead to new device applications.
