Dissertation > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Structural Chemistry > Chemical bond theory

The Study on the Structure, Thermochemistry, and Electron Affinities of Hydrogenated Silicon Clusters

Author LiXiaoJun
Tutor LiChunPing;YangJieCai
School Inner Mongolia University of Technology
Course Chemical processes
Keywords Silicon-hydrogen compounds The structure of the ground state Electron affinity Dissociation energy Density functional theory
CLC O641.1
Type Master's thesis
Year 2007
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Silicon-hydrogen compound attracting much attention in recent years because they are in the modern industry , especially in the microelectronics industry . Density functional theory method : B3LYP, BP W91 and BHLYP fully electronic double ζ plus polarization and diffuse functions basis set (DZP) study Si5Hn (n = 3-12) and Si6Hn (n = 3 -14 ) , get their ground-state structure , electron affinities , resonance frequency, and dissociation energy . Right Si5Hn , when n ≤ 8 , their ground state structure based on five silicon atoms forming trigonal bipyramidal as a basic skeleton , a silicon atom possible four coordination bond connected to a hydrogen atom , when n = 9,10 when , trigonal bipyramidal structures are destroyed , the formation of a cyclic structure , and when n = 11,12 , the ring structure is destroyed , forming a chain and branched structures ; the anionic Si5Hn ? the ground state structure , and neutral Si5Hn and wherein resistance In contrast, when n = 3,8 , their configuration occurs changes , and Si5H3? only formed traditional Si-H bond , is also formed of a non - traditional Si-H-Si hydrogen bridge bond . Of Si6Hn , n ≤ 8 , the ground state structure in double top six silicon atoms form distorted tetrahedron as the basic skeleton , when n gt ; 9 , as n increases , the silicon atoms as possible four ligands bonded hydrogen atom to form a variety of cyclic, chain , and dendritic structures . The ground state structure of the anion Si6Hn? And Si6Hn compared , when n = 7,8,10 and 13 in their configuration obvious changes , major changes in molecular internal silicon skeleton rearrangement . The forecast system key long usually in the order of three methods : BPW91 gt ; the B3LYP gt ; BHLYP . To predict the electron affinity B3LYP and BPW91 forecast of the results is the most reliable results worst of BHLYP projections ; In predicting the dissociation energy , BHLYP largest off hydrogen dissociation energy , produce minimal off hydrogen dissociation energy BPW91 method .

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