The Structures, Spectra And Electronic Bound States Of Electronegative Water-ammonia Mixed Cluster

Clusters are the stable atomic aggregates that are not connected to any peripheral atomsor ligand , such as P4, As4, S6etc. In recent years, by the high temperature jet technology andmass spectrometry analysis, alkali metal, transition metal and semiconductor elements areconfirmed likely to exist with varied clusters form, the most famous result is C60.Along withthe increase of the atom number of the cluster, crystal transition take place at the last. About thedifferent dimensions of the atomic clusters，the data of the structures, energies, the stabilitiesand other properties, provided all kinds of images and regular patterns that from the atoms tomacroscopic solid.Hydrogen bond is the bond that the force intensity intermediate in the intermolecular forceand the covalent bond strength. Hydrogen bond clusters are more important kinds in the clusterfamily, exist in a wide range of water, ammonia, HF and other polar solvents. And by researchof the hydrogen bond clusters (e.g. water ammonia clusters (NH3)m(H2O)nand pure waterclusters (H2O)n), will provide important basis of the law understanding of solvent processes andthe droplet formation in the microscopic and submicroscopic level. As the initial structures ofadditional electronegative clusters are difficult to determine, therefore, scientists are mainlyfocused on neutral hydrogen bond clusters and proton hydrogen bond clusters, while theresearches of the negative charged clusters are relatively less. However, the interactions of thechemical processes between additional electrons and molecular are contact with many scientificfields,including radiation chemistry, biological chemistry, atmospheric chemistry andpharmaceutical chemistry. The ionizing radiation, photosynthesis, biological macromoleculesand water interaction process are great significance understanding by the study of the extraelectron clusters.Recently, many experimental and theoretical studies on the electronegative pure ammoniaand pure water clusters are carried out, to obtain more in-depth understanding and awareness ofthe interaction and dynamic behavior in the system. These work about electronegative puresolvent cluster structures and electronic bound mode has made great progress, but the researchof electronegative water-ammonia mixed clusters is less. Density functional theory method (DFT) is employed to conduct the structuraloptimization and frequency calculation for water ammonia neutral clusters (NH3)2(H2O)4and anegative cluster [(NH3)2(H2O)4]ˉ, then the stable structures of clusters are confirmed.Furthermore, further research is taken on the excess electron binding states and vibrationspectra of electronic clusters. The results show that, the stable linear structure of[(NH3)2(H2O)4]ˉdid not be found, also do not have complete surface binding electronic states,only the inner binding states. Compared with the corresponding neutral clusters, binding energyof electronegative clusters are small, so some of the more stable of neutral clusters. Each peakof infrared spectrum is basically the stretching motion of the hydrogen atoms between waterand ammonia molecules.The main contents of this paper are shown as follows:In chapter 1, firstly we simply introduce the basic concept, classification, main properties,main research directions, present situation, significance and prospect of cluster.Also on thehydrogen bonding of the related knowledge of the comb.In chapter 2, we introduce some theoretic and computing methods of clusters studies,including variation principle, one electron approximation, density functional theory, the basisfunctions of self-consistent calculation and vibrational frequencies. Then we make a briefanalysis of basis set this paper used, and briefly analyzed the basis set and Gaussian03 program.In chapter 3, density functional theory method(DFT/BLYP) is employed to conduct thestructural optimization and frequency calculation for initial configurations of the [(NH3)2(H2O)4]—clusters. Finally 8 kinds of stable structures are acquired under the 6-31++G(d,p) basissets.Analyzed its stability, electronic bound and vibration spectrum.In chapter 4, In order to compared with neutral clusters, The geometrical structures andinfrared spectra of (NH3)2(H2O)4clusters are investigated using density functional theorymethods(DFT/BLYP) with the 6-31++G(d,p) basis sets．Finally 8 kinds of stable structurescorresponding to charged clusters are acquired, comparative analysis between the neutralclusters and the corresponding electronegative clusters are proceeded.