The NEGF method: capabilities and challenges

This general model has been applied by different authors to all kinds of devices like semiconductor nanowires, carbon nanotubes, molecular wires having different kinds of contacts, both normal and superconducting. Many issues still need to be clarified such as the best choice of basis functions in different problems, but according to the author this approach provides a suitable framework for a wide variety of problems involving nanoscale quantum transport. The objective this paper is to present a simple intuitive description of the NEGF method and draw attention to some areas where important conceptual issues remain to be sorted out. An outstanding feature of this approach is the partitioning of the system into a channel described by an Hamiltonian [H] and "contacts" represented by a self-energy [/spl Sigma/]. This includes not only the obvious metallurgical contacts, but also phonons and other "contact-like" entities.