Adsorption of benzene thiolate on the (111) surface of M (M=Pt, Ag, Cu) and the conductance of M/benzene dithiolate/M molecular junctions:: a first-principles study

To seek more conductive and robust molecular wire junction than that based on An electrodes, we studied the adsorption of a benzene thiolate (-S-C6H5) on the (111) surface of Pt, Ag, and Cu, and the zero-bias conductance of a benzene dithiolate (-S-C6H4-S-) between Pt, Ag, or Cu electrodes by density functional theory. For Pt, the fcc-hollow site is found to be the most stable adsorption site, different from noble metal cases where the fcc-bridge site has the largest adsorption energy. The binding energy of a benzene thiolate on Pt(111) is larger than on noble metal surfaces. We evaluated the transmission coefficients by solving the Lippmann-Schwinger equation and determined the conductance of the molecular wire junction with the Landauer formula. At zero bias, the conductance for a molecular wire supported on Pt contact is higher than those supported on noble metals. (C) 2004 Published by Elsevier B.V.