Theoretical demonstration of symmetric [formula omitted] curves in asymmetric molecular junction of monothiolate alkane

Abstract

A molecular junction of an asymmetric molecule generally demonstrates an asymmetric current–voltage ( I – V ) curve, due to the unequal voltage drops at the two molecule–electrode contacts. However, for asymmetric S ( CH 2 ) n CH 3 molecules, symmetric I – V curves are always obtained in the experimental measurements. Here, we investigate the electronic transport of the Au – S ( CH 2 ) 7 CH 3 – Au molecular junction in order to reveal the mechanism of the symmetric I – V curve with ATK package, in which the density functional theory is combined with Keldysh nonequilibrium Green's function method to calculate the electronic and transport properties of nanoscale systems. And the symmetric I – V curve can be interpreted by the curved surface model, which reproduces curved surface of the top electrode in the experiment.