Electronic structure of passivated Au-38(SCH3)(24) nanocrystal

Energetics, electronic structure, charging, and capacitive properties of ba re and thiol-passivated Au-38 Sold nanocrystals were investigated via densi ty-functional calculations. In the energy-optimized passivated nanocrystal, comprised of a truncated-octahedral face-centered-cubic Au-38 core coated by a monolayer of 24 methylthiol (SCH3) molecules, we find interfacial char ge transfer of about 2e from the outermost gold atoms to the sulfur atoms. The estimated effective capacitance is 0.084 BF, correlating well with rece nt electrochemical measurements. Charging takes place within the molecular layer. Molecular adsorption of dimethyl-disulfide is found to be energetica lly unfavorable for a gold cluster of this size. [S0031-9007(99)08937-1].