Density functional study of the cysteine adsorption on Au nanoclusters

The adsorption of the cysteine amino acid (H-SC beta H-2-C alpha H-NH2-COOH) on the Au-55 cluster is investigated through density functional theory calculations. Two isomers. with icosahedral (I-h) and chiral (C-1) geometries, of the Au-55 cluster are used to calculate Hie adsorption energy of the cysteine on different facets of these isomers. Results, only involving the S(thiolate)-Au bonding show that the higher adsorption energies are obtained when the sulfur atom is bonded to an asymmetrical bridge site at the facet; containing An atoms with the lowest coordination of the C-1 cluster isomer.