Two models of quantum bridges connected with semiconductors or metals
  It is proposed two models describing transport and absorbtion processes that occur in nanoscale fragments of electrical circuits, pulled adsorbed molecules, atomic or molecular chains connecting electrodes. Discrete chain model of a molecular bridge between metallic electrodes considers quantum jumps between atoms containing the chain. The potential approach is represented by three-dimensional Kronig-Penney model. The conductivity theory is developed in a supposition that the main contribution into the electron transfer belongs to non-equilibrium affinity populated states of the bridge. The current-voltage and thermodynamical characteristics are calculated for different cases. Explanations for experimentally obtained step-like dependencies in I-V characteristics and its asymmetry are made. The charging effect and Coulomb blockade effect are discussed. It is shown the essential role of transitions between different bridge's charge states. 
V. N. Evteev, M. V. Moiseenko, E. V. Zhuravel and E. Ya. Glushko   (Pedagogical University, Krivoy Rog, Ukraine)