Electron transport through cyclic disulfide molecular junctions with two different adsorption states at the contact: A density functional theory study

1,2-Dithiolane is a promising anchor group for attaching molecules to metal electrodes in molecular junction devices. This five-membered cyclic disulfide adsorbs on Au surfaces either in a cyclic fashion (with its disulfide bond intact, via molecular adsorption) or in an acyclic fashion (with its disulfide bond broken, via dissociative adsorption). Our density functional theory calculations show that the dissociative adsorption is slightly preferred, but both are stable. We also report nonequilibrium Green's function calculations showing that molecular junctions of cyclic and acyclic 1,2-dithiolanes sandwiched between two gold electrodes exhibit essentially the same insulating current-voltage characteristics at moderate bias voltages, despite the significant difference in their states of adsorption.