Dissertation > Excellent graduate degree dissertation topics show

First-Principles Study of the Adsorption of Ag Atoms and Water Molecules on Silica Clusters

Author: ZhiLiLi
Tutor: ZhaoGaoFeng
School: Henan University
Course: Theoretical Physics
Keywords: Density functional theory (DFT) geometric structures electronic properties optical property
CLC: O561
Type: Master's thesis
Year: 2009
Downloads: 87
Quote: 1
Read: Download Dissertation

Abstract


The adsorption of Ag atoms and water molecules on the silica clusters have been investigated using first-principles density functional theory（DFT）.This dissertation is devoted to report the structure and electronic properties of the two systems.The main content is as follows:On the one hand,the interaction between Ag atoms and（SiO2）n（n=1-7） clusters have been detailedly studied based on DFT with generalize gradient approximation（GGA） with Dmol3.Firstly,we study the adsorption state of one Ag atom on the（SiO2）n（n=1-7） clusters.The results show that the Ag atom preferably binds to silicon atom with dangling bond in nearly a fixed direction.The effect of the adsorbed Ag atom on the bonding natures and structural features of the silica clusters is minor,and the adsorbed Ag atom only causes charge redistributions of the atoms near itself.In addition,the energy gaps between the highest occupied and lowest unoccupied molecular orbitals remarkably decrease compared with the pure（SiO2）n（n=1-7） clusters,eventually approaching the near infrared radiation region.This suggests that these small clusters may be an alternative material which has a similar functionality in treating cancer to the large gold-coated silica nanoshells and the small Au3（SiO2）3 cluster.Secondly,we have analyzed the adsorption of multi Ag atoms on（SiO2）3 cluster.The incoming Ag atoms tend to cluster on the existing Ag cluster leading to the formation of Ag island easily, compared with the Aun（SiOn2）n3 cluster.On the other hand,equilibrium geometries,adsorption energies,and electronic properties of a single water molecule on（SiO2）n（n=1-6） clusters have been investigated based on Gaussian 03.The detailed research indicates that a single water molecule preferably binds to silicon atom with dangling bonds and its plane is nearly parallel to the rhombus connected with itself.The water molecule primarily causes charge redistributions of the atoms near itself using the Mulliken charge analysis.In addition, we also report the interaction between（SiO2）3 cluster and multiwater molecules.Our results show that the hardness and energy gap between the highest occupied and lowest unoccupied molecule orbitals decrease as the number of the water molecules increases. The small silica cluster is not as easy as the nanochains to fracture and the Si-O bond breaking is mainly induced by the relatively isolated H3O molecule.In addition,the infrared and Raman spectra are valuable in distinguishing among adsorption and dissociation of water molecules on silica.

Related Dissertations

  1. A Density Functional Theory Study for Wn C0,± （n=1-6） Clusters,O641.1
  2. A Study for Structure and Properties of OsnN0, ± （n=1-6） Clusters,O641.1
  3. First Principles Study on Electronic and Optical Properties of TiO2 Polymorphs,TN304.21
  4. Boron Clusters and lithium, boron-doped aluminum atom clusters Density Functional Theory Study,O469
  5. Density Functional Theory Studies on the Structures and Electronic Properties of Mo and Mo2N Clusters,O561
  6. Magnetic and Electronic Properties of X/Graphene(X=H,Fe,Co) Systems,TB383.1
  7. Structure and Properties of Bismuth System Low Melting Electronic Glasses,TQ171.1
  8. First-principles Study on Optical Properties of Si Nanoparticles and Ferroelectric Materials,O482.3
  9. Properties of the Noble Metal Modified ZnO Composites,O614.241
  10. Boron nitride monolayer graphene structures like electronic structure and magnetic properties of first-principles study,TB383.1
  11. The Effects of Solvent Environment on the Electronic Properties of Molecular Devices,TN495
  12. First-Principles Research on Bulk Doping and Surface Adsorption of TiO2,TB39
  13. A DFT Study on the Influences of Step Structure and Adsorbed Oxygen on Nickel Surface on Dissociation Process of Methane,O643.36
  14. A Time Dependent Density Functional Theoretical Studies of the Ruthenium(Ⅱ) Complexes,O641.4
  15. Theoretical Investigation for Carbazole and Spirosilabifluorene Derivatives as OLED Materials,O626.2
  16. Simulation for the Absorption and Emission Spectra of Cu～I Complexes,O641.4
  17. Synthesis, Optical Properties and Theoretical Research on Hydrazone Ligands and Their Complexes,O641.4
  18. The Preparation of Noble Metal Nanoparticles and the Application in Raman Spectroscopy,O611.3
  19. Amino acid dipeptide crystal structure and theoretical study of the vibrational spectra,O629.7
  20. Adamantane derivatives and tetrahedral alkyl structure and properties of high energy quantum chemical study,O621.13

CLC: > Mathematical sciences and chemical > Physics > Molecular physics, atomic physics > Molecular Physics
© 2012 www.DissertationTopic.Net  Mobile