Abstract: In this review the highlights of both experimental and theoretical studies on single molecular device as well as the standard elastic electronic transport theory combining with Green′s function technique are introduced concisely. A theoretical study on transport properties of a H2O molecule bridged between two Au(111) surface is carried out by using full self-consistent first-principles method and non-equilibrium Green′s functions method. The results show that there is a strong hybridization between H2O molecule and Au surface atoms of the electrodes. The molecular character of H2O molecule is largely conserved by states of Au atoms of electrodes at a small bias voltage. The potential distribution locates the local region around H2O molecule. The conductance of a single H2O molecule bridged between two Au electrodes is mainly contributed by a single channel.

Key words: Single molecular device, H₂O, Electronic structure, 　Transport property