C_(36)N_4四面體型(T_d)球簇分子之理論研究

Theoretical Study of Tetrahedral Type (T_d)C_(36)N_4 Molecule

孫光中(Kuang Chung Sun) ； 孫光明(Kuang Ming Sun)

《化學》 63卷2期 (2005/06) Pp. 315-328

https://doi.org/10.6623/chem.2005026

摘要

本研究係繼C_(24)N_4球簇分子之後，針對同屬於T_d點對稱群之C_(36)N_4球簇分子所進行之理論計算。為求精確及比較起見，本研究同時採用了密度泛函理論(DFT)、全初始法(Ab Initio)及半經驗分子軌域法等進行計算，並佐証以非區域化能量。全幾何優選(Fully Optimization)係侷限在T_d點對稱下完成，分子軌域及其振動頻率同時經由密度泛函理論(DFT)、全初始法(Ab Initio)及半經驗分子軌域法完成。束縛能(Binding Energy)及各種熱力性質則經由半經驗法中之PM3和AM1法獲得。本研究顯示C_(36)N_4球簇分子為一穩定分子，其本身所具之十個六角環中之四個更是處於共平面狀態，具相當顯著之非區域化效果(Delocalization Effect)，此與C_(24)N_4球簇分子中所具備之四個六角環呈現一上一下（類似己烷）不同，其C - C間之鍵結更類似於富樂球烯C_60中平面六角環之結構。

關鍵字

C_(36)N_4 ； C_(24)N_4、C_(60) ； 球簇分子 ； 密度泛函理論(DFT) ； 全初始(Ab Initio) ； 半經驗分子軌域法 ； PM3 ； 非區域化能量

並列摘要

In this work is succeeding C_(24)N_4 carbon cluster research that directed against belongs to tetrahedral type C_(36)N_4 molecule. Including density functional theory b3lyp/6-31G(d), b3lyp/6-31G basis sets, ab initio Hartree-Fock 6-31G(d), 6-31G, 3-21G, STO-3G basis sets and semiempirical PM3 molecular orbital calculations are carried out on the C_(36)N_4 molecule. The equilibrium geometries are obtained on the fully optimization which constrained T_d symmetry. Molecular orbitals and vibrational frequency are also obtained by density functional theory, ab initio and semiempirical methods. The binding energy and various thermodynamic properties are also calculated via semiempirical PM3 and AM1 methods. All the evidences of this work prove that C_(36)N_4 molecule is a stable heterofullerene structure. The structure of C_(36)N_4 molecule has ten six-membered rings and twelve five-membered rings, but in these ten six-membered rings has four six-membered rings that are completely coplanar unlike C_(24)N_4 molecule that is like n-hexane chair form. These factors cause these four six-membered rings with a remarkable delocalization effect and are very similar to the related six-membered rings on the buckminsterfullerene C_(60) molecule.

並列關鍵字

C_(36)N_4 ； C_(24)N_4 ； C_(36) ； Cluster Molecule ； DFT ； Ab Initio ； Semiempirical MO Method ； Delocalization energy