Effects of the intra-site Coulomb interaction on electron transport in an atom bridge

The effects of the intra-site Coulomb interaction on the electron transport in an atom-sized bridge (an atom bridge) between a metal surface and a tip of a scanning tunneling microscope are investigated with the aid of the Hu bbard Hamiltonian. The second-order self-energy with respect to the Coulomb interaction in a single site approximation is taken into account in calcul ating for the conductance of the bridge. We examine the conductance variati on as a function of the stretching length of the bridge in the case where a n electron-hole symmetry is broken and two types of the conductance jumps r oughly in units of 2e(2)/h and 4e(2)/h exist. Numerical results show that a valley structure and a quasi-plateau appear at the upper side of the condu ctance jumps roughly in units of 4e(2)/h at low temperatures and at high te mperatures, respectively. On the other hand, the reduction of the conductan ce is small and monotonic at the conductance jumps roughly in units of 2e(2 )/h. (C) 2001 Elsevier Science B.V. All rights reserved.