Adsorbed On The Anionic Gold Clusters, Gold Clusters And Sh

Clusters have the size between those of atoms and macroscopical systems, and have many unique properties. So many experimental and theoretical researches have been done on them. Even more focus has been put on gold clusters, because they have a unique ability to catalyze some reactions of small molecules. Studying the adsorption properties of small molecules on gold cluster is the first job. Along with the rapid development of computes, with moderate computational consume and high precision, density functional theory (DFT) has become one of the most important methods in computational chemistry. This paper is a DFT study of gold clusters and the adsorption properties of small molecules on gold clusters.In Chapter 1, we give a brief introduction to clusters and gold clusters. At following, we introduce the basic properties of clusters, common methods using in experimental and theoretical studies on cluster,gold custers, the basic properties, and the research progress of CO oxidation on gold cluster.In Chapter 2, we introduce the basic concept and progress of DFT. Development of quantum chemistry promotes the establishment of DFT. Thomas-Fermi model is the first theory using density of electrons as the main variable. Theorem of Hohenberg-Kohn is the fundament of DFT and is developed to Kohn-Sham equation, which can be used to perform real calculations. At the end of this chapter, we introduce the software Gaussian briefly.In Chapter 3, Geometries and electronic properties of neutral, anion, cation of Aun (n=2⁶) cluster are investigated by two methods of density functional theory (DFT) B3LYP and BPW91.All the optimal geometries calculated are planar. Odd-even oscillation effect occurs in the binding energy, the second difference of binding energy, HOMO-LUMO gap, Electron affinities ( EAs) , Ionization potentials ( IPs), except the'Y-shape'of Au4 cluster, whose dipole momentum isn't 0.000. The stabilization of these which contain electron-pair even number is superior to that of odd number clusters. Difference in stabilization firmly correlates to electron-pair effect in gold clusters.In Chapter 4, the adsorption properties of SH molecule on anionic Au_n^- clusters (n=1-6) are studied by using the DFT method. Then adsorption properties of SH molecules on anionic Au_n clusters (n = 1-6) are studied by using the DFT method with the generalized gradient approximation (GGA), and with the hybrid functional. But the adsorption of O₂ is only investigated with the hybrid functional. Our results show that the GGA calculations with the BPW91 functional systemically overestimate the adsorption energy by 0.1 eV than the hybrid DFT ones with B3LYP functional. The binding energy is found in an even-odd manner, the structures are incline to planar .The charge transfer from the clusters to SH, and the length of the bond SH almost hold the line. Via the contrast of binding energy between oxygen and mercaptotropolone adsorption on gold clusters, the O₂'s is much bigger than SH's.At last the vibrations of SH adsorption on gold clusters are studied.