Theoretical study of thiol-induced reconstructions on the Au(111) surface

Theoretical study of thiol-induced reconstructions on the Au(111) surface

by L. M. Molina and B. Hammer.

Chem. Phys Lett. 360, 264-271 (2002).

Abstract

A new suggestion for the structure of the Au substrate underlying Self-Assembled Monolayers (SAM) made of thiols is presented on the basis of density functional theory results for methylthiolate (-SCH$_3$) adsorption on Au(111). It is found that by introducing vacancy defects on the substrate, the adsorption of SCH$_3$ is stabilized by about 0.8 eV with respect to the perfect Au(111) surface. As this overcomes the vacancy formation energy ($\approx$ 0.6 eV), a net driving force exists leading to an adsorbate-induced reconstruction, that enhances adsorption at defected Au(111). A comparison of results at high and low SCH$_3$ coverage provides further insight into which specific gold vacancy sites enhance the adsorption energy of the SCH$_3$ molecule.