On the Thermodynamic Stability of (√3 x √3)R30° Methanethiolate Lattice on Reconstructed Au(111) Surface Models

We present a comparative study of the adsorption energy and the thermodynamic stability of the (root 3 x root 3)R30 degrees methanethiolate (MT) lattice on different reconstructed Au(111) surfaces based on density functional calculations. Results show that all adatom-containing surface models exhibit the same or lower thermodynamic stability than the unreconstructed Au(111) surface. In contrast the (root 3 x root 3)R30 degrees methanethiolate lattice on vacancy-rich surfaces has been found to be stable with respect to the unreconstructed surface. The thermodynamic stability of the different surfaces results from the energy balance between the cost to form the reconstructed Au surfaces and the energy gain due to a more favorable adsorption of the MT species.