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Study on the Structure and Growth Mechanism of Silica Anion Magic Cluster

Author: GaoChenYang
Tutor: XuCan
School: Lanzhou University
Course: Optics
Keywords: anion cluster magic cluster density function theory growth mechanism
CLC: O561
Type: Master's thesis
Year: 2006
Downloads: 43
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Abstract


The atomic cluster is one of elementary building unit which form nanometer material. Its geometric structure and electronic structure have become an important topic in the design of the micro structure. Due to the wide application of silicon oxide and special nature of corresponding nanometer material, silicon oxide nanoclusters have drawn much attention. In the last decade, the properties of silicon oxide nanoclusters have been largely studied. On the one hand, it tests the results of experiment;on the other hand, it provides theoretical guidance for the experiment. Based on the experiment, we study silica anion cluster using DFT method. The full text contains the following three parts:Ⅰ. Study on the structure and stablities of anion cluster（SiO2）nX-3MR （three-membered ring） structure, 2MR （two-membered ring） linear chain structure and pseudotetrahedral cage structure have been proposed for the anion cluster （SiO2）nX-（n=15 X=, 0, OH）. The geometric structure, average binding energy, energy gap and Laplas density are performed by the DFT theory at the B3LYP/6-311+G* level. It is predicted that the formation of （SiO2）4O2H3-may depend on the structure of （SiO2）4OH-.Ⅱ. DFT theoretical study on the structure of magic clusterSeven typical structures of magic cluster （SiO2）8O2H4 are present. The stabilities of structures and energy gap have been analyzed using B3LYP with 6-31+G** basis set. It is confirmed that double-cage structure and cubic structure are more stable than others. The result of energy gap indicates that these two structures are inclined to form larger cluster.Ⅲ . The growth mechanism of magic cluster from （SiO2）4O2H3- to （SiO2）8O2H3-Two growth mechanisms from （SiO2）4O2H3- to （SiO2）8O2H3- are proposed.Geometrical structures are optimized via density function theory with 6-31+G** basis set. Average binding energy, the second-order energy difference and the orbital of HOMO are systematically discussed, which confirms that both growth mechanisms are reasonable.

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CLC: > Mathematical sciences and chemical > Physics > Molecular physics, atomic physics > Molecular Physics
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