Electronic properties of a quantum wire interacting with a surface: the role of periodically placed impurities

The transmittance and density of states (DOS) of a quantum wire which is tunnel coupled to the underlying substrate are investigated theoretically using the retarded Green's function method. The wire is composed of periodically placed impurities with Coulomb interactions and is modeled by a tight-binding Hamiltonian within the mean-field approximation. For a given periodicity of impurities along the wire we observe energy gaps in the structure of DOS. These gaps disappear for a wire coupled with the substrate electrode with localized electrons which leads to a metal–insulator transition in the system. Our numerical studies reveal that the transmittance through the system strongly depends on whether or not the substrate electrons are localized. (paper)