Soliton effects in dangling-bond wires on Si(001)

Dangling bond wires on Si(001) are prototypical one-dimensional wires, which are expected to show polaronic and solitonic effects. We present electronic structure calculations, using the tight binding model, of solitons in dangling-bond wires, and demonstrate that these defects are stable in even-length wires, although approximately 0.1 eV higher in energy than a perfect wire. We also note that in contrast to conjugated polymer systems, there are two types of soliton and that the type of soliton has strong effects on the energetics of the band gap edges, with the formation of intragap states between 0.1 and 0.2eV from the band edges. These intragap states are localized on the atoms comprising the soliton.