Theoretical Chemistry Studies On Na_n Cl_n+1 Clusters And Cl Adsorbed On Crystal Face (001) (111) Of NaCl

Sodium chloride crystal is a typical Alkali halide crystal,in which, ions are connected with typical ionic bond. The study on sodium chloride will give spark on understanding the crystal growth, surface decorating and functional materials designing. Additionally, there are a mass of aerosol containing sodium chloride, which exists in polar region and sea surface, and, there are also plentiful such particulate matter containing sodium chloride. Chemical processes of atmospheric transient species react with such partical release active halogens, which contribute greatly to ozone layer destruction. To understanding such chemical process in atmosphere, it is necessary to carry out deep studies on the electronic structure and chemical properties of sodium clusters.In this thesis, the geometry and electronic structure of (NaCl)_nCl clusters and their anion, as well as Cl absorbed on NaCl crystal surface have been studied with quantum chemistry method combined with topological analysis on electronic density. By analyzing the topological properties on bond critical point, the nature of bonding has been discussed.In Chapter one, the application of clusters, metal halide clusters and sodium chloride, as well as the research importance have been summarized briefly. Detailed analysis on the research results on neutral sodium chloride clusters and their ions, as well as the reaction and adsorption on NaCl crystal surface,has been carried out. In this section, the development and application of topological analysis of electronic density have also been introduced briefly.In Chapter two, the basic theory of quantum chemistry has been given, and also the basic idea of topological analysis of electronic density.In Chapter three, system study on (NaCl)_nCl (n=1-6) and their anions has been carried out. The cluster geometry, binding energy of Cl /Cl^- on (NaCl)_n, electronic structure have been calculated at B3LYP level with /6-311+G(3df) basis set. The nature of chemical bonding in these clusters has been revealed with topological analysis of electronic density method. Influence on the electronic structure and chemical bonding of the cluster with additional electron on neutral cluster has been discussed.In chapter four, based on a suitable model of NaCl face (001) and face (111), Cl absorption on such surface has been studied with quantum chemistry calculations and topological analysis of electronic density. The preferable absorption sites on such surface have been found.The main innovative points of this paper : 1. Cluster geometry of (NaCl)_nCl (n=1-6) and (NaCl)_nCl^– (n=1-6) has been given, and a special structure of Cl₂^- has been found, which is bonding covalently. The formation of Cl2- can be seen as a replacement of Cl^- in NanCln cluster with Cl2-.2. The addition of an extra electron in (NaCl)_nCl (n=1-6) changes the electronic structure of the cluster, and the geometry changes correspondingly.3. Among the four topological index of (?)²Ï,Γ_C, |λ₁|/λ₃, G/ρ_C, G/ρ_C has been found the best one to describe the bonding charater for the ionic bonding cluster.4. By comparing the binding energy, Cl is prone to absorbed on Cl in face (001), while is prone to absorbed on Na in face (111) of NaCl.5. When absorbing Cl on Cl site in face (001) and (111) of NaCl, Cl₂^- has been formed. The net charge on the two Cl in such Cl₂^- is different depending on the crystal face of NaCl.6. Non - Nuclear Attractors have been found in absorbing system of Cl on crystal face (111), indicating the apparent change of electronic structure during the absorption.7. When Cl has been absorbed on Na site of face (111), electron transfers from Cl layer to absorbed Cl, and chang the absorbed Cl to Cl^-.8. The formation of Cl₂^- in some neutral cluster of (NaCl)nCl and absorbed system of Cl on face (001) and (111) of NaCl change the interaction between the Cl in Cl₂^- with Na, this may provide an possible way to release active halogen to atmosphere.