Effects of intra-site Coulomb interaction on quantized conductance in a quantum wire between an STM tip and a metal surface

Effects of the intra-site Coulomb interaction between electrons on the quantized conductance in a quantum wire are investigated with the aid of the Hubbard Hamiltonian. The second-order self-energy with respect to the Coulomb interaction is taken into account within a single site approximation for calculating the conductance of a quantum wire. Owing to inter- and intra-subband electron–electron scattering at finite temperatures caused by the Coulomb interaction, the conductance is found to deviate from the quantized value, 2 Ne 2/ h (where N is an integer). Furthermore, in the case where the subband edge lies energetically near the Fermi energy, the valley appears in the conductance as a function of the stretching length of the wire.