Study of the adsorption of thiols on Au 55

1. Study of theadsorption of thiolson Au55 Dhiraj K. Sardar, University of Texas at San Antonio, DMR 0934218 In the new nanotechnology devices design, the study of the interaction between nanoparticles and different types of ligands has been a very important topic. The control of the adsorption and the appearance of structural changes on ligand passivated gold nanoparticles are of primary importance in the design of biocompatible materials, biosensors, single electron tunneling devices, catalysis and many other applications. Initial Goal: To perform ab initio density functional theory simulations with the SIESTA code to determine the most stable adsorption sites, and specify the most favorable adsorption modes for the methyl-thiol molecule on an icosahedral Au55 cluster. In collaboration with our colleagues from Northwestern, we recently found that the favorable absorbed sites for the thiol molecule were on Bridge sites. We are extending this approach to the case in which the cluster is capped with two and more molecules. Currently our PREM research is focused in the development of a classical force field from ab initio calculations in order to extend this study to larger-size nanoparticles and longer timescales. T - Top H - Hollow B - Bridge B (SCH3) Thiol H T Hector Barrón Escobar (PhD Student) Dr. XóchitlLópez-Lozano Eads= Etot(Cluster+Thiol)-Etot(Cluster) - {Etot(Thiol)-1/2 E(H2)}