| 摘要: | 本研究是以B3LYP/LANL2DZ方法探討的是鹼土族金屬原子吸附在小型鍺團簇(Ge6~Ge8)上之能量最低的結構與最佳穩定的狀態，並探討其金屬複合團簇的結構之鍵長、結合能、電荷轉移、HOMO-LUMO gap。此研究中我們利用鹼金族金屬原子吸附在小型鍺團簇(Ge6~Ge8)之表面與鹼金族金屬原子吸附在負離子的小型鍺團簇(Ge6－~Ge8－)之表面來做比較後者與AEMGen等電子。
我們的結果顯示BeGen是所有複合團簇中吸附能最大的這也發生在對應的BeSin中。一般而言Be-Ge鍵比起其他M-Ge鍵強，且Be的鍵結容量至少高過共價鍵理論所預期的同一個單鍵以上。然而BeGen的穩定度仍然不及Gen+1，這表示Ge-Ge鍵比Be-Ge鍵強。這似乎很合理，因為Ge是4A族元素，其鍵結容量理應比2A族的Be大。另外原子半徑的差異也會造成相對鍵結強度的不同。
In this thesis, we report some lowest-energy structures and the most stable state of alkaline earth metal (AEM) atom adsorbed on the small germanium cluster Ge6~Ge8 at the B3LYP/LANL2DZ level. We also investigated their HOMO-LUMO gaps, charge distribution, binding energies、Mayer Bond Orders and Mayer Total Valences. We compared with the above clusters with those of alkali metal atoms adsorbed on the surface of small germanium clusters and alkali metal atoms adsorbed on the anion group of small clusters of germanium surface(Ge6－~Ge8－), which is isoelectronic with the AEM-Gen(n=6~8)clusters.
Our results reveal that BeGen are always the ones having the highest adsorption energy among add other hybrid clusters. Generally speaking, Be-Ge bonds and strong then other M-bonds and the bonding capacity of Be is at least one more single bond than the valence bond theory world predict. however, the stability of BeGen is still lower than Gen+1, which indicates that Ge-Ge bond is stronger then Gen+1, which indicates that Ge-Ge bond is stronger then Be-Ge bond. It looks like to be so because Ge, the 4A element, should have higher bonding capacity than Be, the 2A element. Also the relative atomic radii of Be and Ge count the relative bonding strength. |
