Coherent Electron Transport in Molecular Contacts: A Case of Tractable Modeling
This chapter provides a researcher with the necessary requisites for independent modeling of coherent electron transport through a single molecule connecting two metal/semiconductor leads. It describes how the tunneling exponent behaves when the barrier top is biased by external voltage; when further increase of the bias tunes the tunneling energy to a field-induced, triangular-shaped well and when bias is large enough to create the Wannier—Stark band and to make its bottom lower than the tunneling energy. The chapter examines a two band tight-binding Hamiltonian, which describes valence and conduction bands divided by the gap of forbidden states. It explains an analytically tractable model of organic oligomers — aclass of molecular wires, is formulated on the basis of the established Hamiltonians that reproduce essentials of the electronic structure of real conjugated and saturated molecules. Exact explicit expressions of M — and -oligomer Green’s functions have been formally elaborated in physically sound contexts, and illustrated by representative examples.