1 Theoretical Nanoelectronics Group, Theory Section, Department of Micro- and Nanotechnology, Technical University of Denmark2 Theory Section, Department of Micro- and Nanotechnology, Technical University of Denmark3 Department of Micro- and Nanotechnology, Technical University of Denmark4 Center for Nanostructured Graphene, Center, Technical University of Denmark5 The Institute of Chemical and Physical Research6 University of Tokyo7 University of Tokyo
We consider the effect of a finite voltage bias on the conductance of single-atom gold contacts. We employ a nonorthogonal spn-tight-binding Hamiltonian combined with a local charge neutrality assumption. The conductance and charge distributions for finite bias are calculated using the nonequilibrium-Green-function formalism. We calculate the voltage drop through the contacts and find the main drop located near the negative electrode. We argue that this is due to the filled d-state resonances. The conduction is analyzed in terms of transmission eigenchannels and density of states of the eigenchannels projected onto tight-binding orbitals. We find a single almost fully transmitting channel with mainly s character for low bias while for high bias this channel becomes less transmitting and additional channels involving only d orbitals start to conduct.
Physical Review B (condensed Matter and Materials Physics), 1999, Vol 60, Issue 24, p. 17064-17070