Adsorption of Cysteine on the Au(110)-surface: A Density Functional Theory Study

We present ab initio studies towards the adsorption of the amino acid cysteine on the Au(110) surface. By means of density functional theory calculations and using the repeated-slab supercell method, we investigate three main aspects relevant for the adsorption process. First, in order to estimate the slab width required for an accurate description of the gold surface, we calculate the surface energies for both the unreconstructed and the missing row (1×2) reconstructed Au(110) surface for varying slab widths. Then, we determine the formation energies for vacancies in the salient row on the missing-row reconstructed surface. This allows us to estimate the energy cost for a local lifting of the missing-row reconstruction upon molecular adsorption. Finally, we examine the formation of cysteine dimers via carboxyl-carboxyl hydrogen bonds and investigate the changes in the bond energy caused by intermolecular strain. We predict the cysteine dimer formation in Au surface vacancies to play an important role in the adsorption process.