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系統識別號 U0026-2906201422142500
論文名稱(中文) 利用天然鍵結軌域分析甲基超共軛效應的一種新看法
論文名稱(英文) A New Look on Hyperconjugation of A Methyl Group Provided by NBO Method
校院名稱 成功大學
系所名稱(中) 化學系
系所名稱(英) Department of Chemistry
學年度 102
學期 2
出版年 103
研究生(中文) 游旨儼
研究生(英文) Chih-Yen Yu
學號 L36014265
學位類別 碩士
語文別 中文
論文頁數 136頁
口試委員 指導教授-王小萍
口試委員-黃福永
口試委員-施良垣
中文關鍵字 密度泛函理論  天然鍵結軌域  波函數分析  超共軛效應 
英文關鍵字 density functional theory  natural bond orbital  wavefunction-analysis  hyperconjugation 
學科別分類
中文摘要 本論文用理論計算的方法,來研究物質的性質,以量子力學為基礎,使用的計算方法為HF理論(Hatree-Fock theory)和密度泛函理論(density functional Theory, DFT),而以DFT較為常用,選用的計算軟體為高斯03,輔以Gauss View建構分子,之後做最佳化結構的運算,再做天然鍵結軌域(natural bond orbital, NBO)的計算,並分析各個分子的成分NBO對HOMO、LUMO的貢獻度,以及能量的影響。本論文分兩個部分,第一部分主要研究氣相條件下,簡單醇類化合物的酸性排序,包含了水、甲醇、乙醇、正丙醇、異丙醇、第三丁醇、苯酚,藉由NBO的分析,討論不同取代基對HOMO、LUMO能量的影響,進而用HOMO、LUMO能量的高低,推論出該系列分子的鹼性大小。經過不同基底的運算,可以得到最佳的計算方法為DFT B3LYP/STO-3G,其鹼性大小結果為: 第三丁醇>異丙醇>正丙醇>乙醇>甲醇>水>苯酚,而該方法所得的結果與真實實驗數據是一致的。第二部分則解釋氣相條件下,一些苯環衍生物的紫外光譜(UV-vis spectrum),包括了苯、甲苯、苯酚、苯胺、氟苯。透過NBO分析,可以觀察出取代基,尤其是孤對電子(lone pair),對苯環主結構HOMO、LUMO能量造成的改變。選用的計算方法為DFT B3LYP/6-31G(d),其結果顯示,HOMO、LUMO之間的能量差為: 氟苯>苯>甲苯>苯酚>苯胺,這和紫外光譜的結果一致,理論計算做出很成功的預測。以上兩部分都是研究取代基對邊界軌域(frontier orbital)能量造成的影響,並做波函數的分析,發現除了誘導效應(inductive effect)外,還有軌域作用(orbital interaction)的影響,而軌域作用中的超共軛效應(hyperconjugation)或負超共軛效應(negative-hyperconjugation)更扮演重要的角色。本論文用理論計算去解釋這些現象,除了印證真實實驗數據之外,也能做為日後預測類似分子性質時的參考。

關鍵字:密度泛函理論; 天然鍵結軌域; 波函數分析; 超共軛效應
英文摘要 In this thesis, we present the rationalizations of (1) relative basicity regarding molecules containing hydroxyl group and (2) the UV spectra reported for benzene derivatives. This is achieved by ab initio studies, including Hatree-Fock (HF) and density functional theory (DFT) methods employing the Gaussian computational packages. The natural bond orbital (NBO) method has also been adapted to probe the nature of various substituents, especial of methyl group. The fundamental and/or essential wavefunction-analysis has been performed was employed to quantify the extents of substitution. In the course of this investigation, it has been found that the B3LYP/STO-3G calculations provide the best predictions. In both areas of this research, the orbital interaction approach reported recently provides an insight of hyperconjugation associated with the methyl group as it is introduced to unsaturated systems. Within this approach, the CH bond orbital (BO) of a methyl group would destabilize (or push-up) the one-center BO, lp(O), on the methyl oxygen. Consequently, this lone-pair orbital turns more basic. This destabilization effect is more pronounced on the -type HOMO of benzene, which leads to a reduced HOMO-LUMO gap.

Key words: density functional theory; natural bond orbital; wavefunction-analysis; hyperconjugation
論文目次 中文摘要 I
Abstract II
誌謝 VI
目錄 VII
表目錄 X
圖目錄 XII
第一章 緒論 1
第二章 理論背景 4
2.1 量子力學(Quantum Mechanics)的基本概念 4
2.1.1 波粒二象性(duality) 5
2.1.2 薛丁格方程式 5
2.1.3 波恩詮釋(Born Interpretation) 6
2.1.4 歸一化(Normalization) 7
2.1.5 特徵方程式(Eigenvalue Equation) 7
2.1.6 期望值(Expectation Value) 8
2.1.7 海森堡測不準原理(Heisenburg Uncertainty Principle) 9
2.2 運動的量子化 9
2.2.1 移動(Translational Motion)的量子化 9
2.2.2 正交性(Orthogonality) 12
2.2.3 穿隧效應(Tunnelling) 13
2.2.4 振動(Vibrational Motion)的量子化 14
2.2.5 簡諧振盪子的穿隧效應(Harmonic Oscillator Tunnelling) 15
2.2.6 轉動(Rotational Motion)的量子化 16
2.2.7 空間方向的量子化(Space Quantization) 20
2.2.8 自旋(Spin)的量子化 20
2.2.9 微擾理論(Perturbation Theory) 21
2.3 原子結構 23
2.3.1 量子數(Quantum Number) 23
2.3.2 類氫原子的波函數 24
2.3.3 Radial Distribution function 26
2.3.4 s軌域 28
2.3.5 p軌域 29
2.3.6 d軌域 30
2.3.7 選擇律(Selection Rule) 30
2.3.8 Orbital Approximation 31
2.3.9 庖立不相容原理(Pauli Principle) 32
2.3.10 Spin Correlation 34
2.3.11 構築原理 36
2.3.12 Spin-Orbit Coupling 37
2.4 分子結構 38
2.4.1 波恩近似(Born-Oppenheimer Approximation) 38
2.4.2 價鍵理論(Valence Bond Theory) 39
2.4.3 分子軌域理論(Molecular Orbital Theory) 41
2.4.4 異核雙原子分子(Heteronuclear Diatomic Molecules) 44
2.4.5 Variation Principle 45
2.4.6 Hückel Approximation 50
2.4.7 超共軛效應(Hyperconjugation) 52
2.5 計算原理 53
2.5.1 HF理論(Hartree-Fock theory) 53
2.5.2 密度泛函理論(Density Function Theory) 55
2.5.3 基底 58
2.5.4 分裂(Split)基底 59
2.5.5 極化函數(Polarization function) 59
2.5.6 擴散函數(Diffuse function) 60
2.5.7 天然鍵結軌域(Nature bond orbital, NBO) 60
第三章 計算方法 63
3.1 選用軟體-Gaussian 03 63
3.2 GaussView 63
3.3 計算指令 63
3.4 選用基底 64
第四章 結果與討論 65
4.1簡單醇類分子的鹼性次序 65
4.1.1 簡單醇類分子的NBO分析 65
4.1.2 取代基對鹼性的影響 83
4.1.3 不同計算方法對結果的影響 85
4.1.4 理論計算與實驗數據的比較 96
4.2 超共軛效應對光譜的影響 97
第五章 結論 107
參考文獻 108
附錄1 各醇類分子的最佳化結構圖 110
附錄2 各醇類分子電子雲分布圖 116
附錄3 科學月刊文章幾則 127
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