臺灣博碩士論文加值系統

本論文的研究分為四部份，第一章為含有惰性氣體陰離子FHeO—之理論研究，第二章為甲酸乙酯熱分解反應的動力學研究，第三章是以多層電子結構方法(MLSEn+d)計算原子化能量及能量障礙，第四章 HHeF ® He + HF 反應的動力學研究。茲摘要敘述如下:
在第一章的研究中，我們利用高階的全初始法 (ab initio)研究含有惰性氣體的陰離子FHeO―之結構及相對能量，結果發現其在單一態( singlet )有一個穩定的能量的最低點且其能量比三重態 ( triplet state )明顯低很多。同時也發現出FHeO― → He + FO―的分解反應有很高的解離能量障礙。此陰離子穩定性的來源是由於氟離子會誘導O=He鍵的形成。此章研究的結果顯示此陰離子甚至是此類型的離子化合物有可能可以在低溫的條件下被實驗觀察到。

在第二章的研究中，我們以全初始法及電子密度泛函理論，並配合雙層動力學的計算研究甲酸乙酯在溫度為100-1000 K之間的熱分解反應(thermal elimination reaction)的反應速率。計算結果顯示其在500 K以下反應主要是穿隧效應( tunneling effect )進行，含有穿隧作用所估計的反應數率常數(CVT/SCT)和實驗值非常接近。

在第三章的研究中，我們針對第三週期的元素使用較佳的基底函數來改善我們實驗室發展的多層電子結構的方法(MLSEn)來計算原子化量能量及中性系統的反應能量及障礙，此新的方法命名為MLSEn+d。我們根據更新過的109個原子化能量、38個氫轉移反應的能量障礙及最近發展的非氫轉移反應資料庫中的22個中性反應能障做參數最佳化。此新的方法對此三種類型能量的測試有不錯的結果，其中最好的方法MLSE4+d對此三種類型能量的平均絕對誤差分別為0.70、0.87及0.69 kcal/mol。

第四章的研究中，我們以雙層VTST/QRST(variational transition state theory with quantized reactant state tunneling)理論計算HHeF進行氣相分解反應時在溫度20 K到1000 K時的反應速率常數。 溫度在600 K以下時，反應的發生主要靠穿隧效應的作用，反應速率常數在250 K以下幾乎和溫度無關。HHeF分解為He + HF的途徑以CCSD(T)/aug-cc-pVQZ所計算的能量障礙為7.80 kcal/mol，相較於相同解離路徑的HArF及HKrF其能量障礙是很低的，所以其反應速率相對的快釵h，所以我們認為這是目前HHeF在實驗上無法觀察到的主要原因。

This thesis consists of four chapters .The first is theoretical prdiction of noble-gas containing anions FHeO—, the second is dynamic study for ethyl formate syn elimination reaction , the third is improved multi-level electronic structure methods (MLSEn+d) for atomization energies and reaction energy barriers, the fourth is rate constant calculation for HHeF →He+ HF reactions by variational transition state theory.

In chapter 1, the structures and energies of the noble-gas containing anions FHeO- have been calculated by high-level ab initio calculation. The FHeO- were found to be deep energy minima at the singlet electronic state and their energies are significantly lower than those at the triplet state. High dissociation energy barriers to He + OF- were also predicted. The unexpected stability of the FHeO- was due to the dramatic ion-induced O=Ng bond formation. The calculated results suggested possible experimental identification of the anionic species and even some related “ionic compounds” under cryogenic conditions.

In chapter 2, the thermal elimination reaction has been studied by density functional theory (DFT) and ab initio method , we also use dual –level variational transition state theory to calculate the rate constant at 100-1000 K. The calculated results show that tunneling was found to dominate the reaction below 500 K, and compared to experimental values, the rate constant included tunneling(CVT/SCT) is very closed to experimental values.
In chapter 3, We have improved our multi-level electronic structure methods MLSEn for calculating the atomization energies and reaction energy barriers for neutral systems by using improved correlation-consistent basis sets for second-row elements. The re-parameterization of the improved methods MLSEn+d was based on updated databases of 109 atomization energies, 38 hydrogen-transfer barrier heights, and 22 neutral reaction barrier heights from a recently developed database of non-hydrogen-transfer reactions. The improved methods perform very well on all three types of energies with mean unsigned errors of 0.70, 0.87, and 0.69 kcal/mol by the MLSE4+d method.

In chapter 4, The rate constants for the gas-phase dissociation of HHeF through the bending coordinates have been calculated using the dual-level variational transition state theory with quantized reactant state tunneling
(QRST) from 20 to 1000 K, Tunneling was found to dominate the reaction below 600 K, and the rate constants were found to be approximately temperature independent below 250 K. The barrier of HHeF dissionation to He +HF at CCSD(T)/ag-cc-pVQZ level is 7.8 kcal/mol, compared to HArF and HKrF, the barrier is low and then the rate constant is very fast. We think that that is the reason why can not find HHeF in experiment.

總目錄
頁次
中文摘要………………….……………………………………………..i
英文摘要………………….……………………………………………..iii

第一章 含有惰性氣體陰離子FHeO—之理論研究
1.1 前言…………………………………………………………..1-2
1.2 計算方法……………………………………………………..1-5
1.3 結果與討論…………………………………………………..1-6
1.4 結論………………………………………………………....1-11
1.5參考文獻………………………………………..…………...1-12
圖表……………………………………………………………...1-14

第二章 甲酸乙酯熱分解反應的動力學研究
2.1 前言…………………………………………………………..2-2
2.2 計算方法……………………………………………………..2-4
2.3 結果與討論…………………………………………………..2-6
2.4 結論………………………………………………………....2-10
2.5參考文獻…………………………………………………….2-11
圖表……………………………………………………………...2-13
第三章 以多層電子結構方法 (MLSEn+d)來計算原子化能量及能量障礙
3.1 前言…………………………………………………………..3-2
3.2 計算方法…………………………..……………………........3-5
3.3 結果與討論…………………………………………………..3-7
3.4 結論…………………………………………………………3-11
3.5參考文獻……………………………..……………………...3-12
圖表……………………………………………………………...3-14

第四章 HHeF ® He + HF 反應的動力學研究
4.1前言…………………………………………………………..4-2
4.2 計算方法……………………………………………….........4-4
4.3 結果與討論…………………………………………………..4-6
4.4 結論………………………………………………………....4-11
4.5參考文獻…………………………………………..………...4-12
圖表……………………………………………………………...4-15

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