Quantized conductance of Si atomic wires

We have performed first-principles pesudopotential calculations of the quantum transport properties of a chain of Si atoms connected to the outside through long leads. By solving a three-dimensional quantum scattering problem we have computed the conductance for several atomic wires with up to eight Si atoms. The Si atomic wires are found to be metallic and we observed quantized conductance in units of ${2e}^{2}/h.$ A conductance dip is found to develop near the onset of the second quantized plateau as the number of atoms increases, and this can be explained by the existence of a gap in the density of states when the atomic chain is infinitely long.