Computational Study of Alkaline Earth Metal Atom on Si7~Si9 Silicon Clusters
| Autor: | Wei Lu, 呂瑋 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 In this these, geometric optimizations, single point energies, and HOMO-LUMO gap were calculated at the B3LYP/6-311++G(3df)groups, respectively. Total energies of all Sin and MSin clusters increase with n and metal size because as n increases number of electrons grows. However, if we look at the average binding energy which is relavent to cluster stability, we find that although stability still increases with n, BeSin and CaSin are more stable than MgSin at the same n. Form Hirshfeld changes, one knows that Be-Si bonds are very covalent while Ca-Si bonds are much move ionic, both effects result into lower-energy clusters. On the other hand, Mg-Si bond are less covalent and less ionic, hence MgSi clusters are the weakest ones. HOMO-LUMO gap is more complicated, it may be affected by covalency and iconicity, but in general BeSin have the highest valne than other hybrid clusters. Although Mayer bond order of Be-Si is the largests and Ca-Si is the smallest among M-Si bonds, BeSin and CaSin has very similar average binding energies, indicating MBO may underestimate the ionic contribution. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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