I.量子化學計算之分子間作用力 II.干涉態對於量子主導方程式的影響

Abstract

本論文包含了靜態的量子化學計算以及動態的量子動力學。第一章以氫鍵與鹵素鍵為系統，基於量子化學計算探討系統內的分子間作用力與質子轉移機制。第二章以雙量子態為模型探討在開放系統中密度矩陣隨時間的演化。 在氫鍵系統中我們選擇醯胺分子對於其N-H…O=C型的氫鍵進行研究，在微擾理論MP2/aug-cc-pVDZ的計算下得到丙烯醯胺的單體以及雙體結構，其雙體結構因N-H…O=C氫鍵的影響在振動光譜上相較於單體會有紅移的現象。此外，我們也引用了密度泛函理論ωB97XD/aug-cc-pVDZ對於甲醯胺與甲酸的雙體及其混合物進行質子轉移的研究，在質子轉移的過程中位能曲面，質子受力，電通量變化都有著對應的關係。對於雙質子轉移的過渡態我們以symmetry adapted perturbation theory做了能量分類，顯示出雙質子轉移的活化能多半來自於電子交換能。對於鹵素鍵的系統我們選擇CF3Cl及CF3Br為路以式酸，搭配不同型態的路以式鹼(1孤對電子、2孤對電子、1孤對電子與未飽和鍵以及π鍵系統)形成雙體，在雙體的結構下探討取代效應、路以式鹼的形態對於分子間作用力的影響。此一研究顯示以CF3Cl及CF3Br為路以式酸的鹵素鍵系統在光譜上皆屬藍移型鹵素鍵，而傳統用於解釋鹵素鍵的σ模型在分子系統逐漸增大的狀況下必須加入其他因素做為微調(例如氫鍵)。 另一方面，對於開放系統我們以馮•紐曼的量子主導方成式為基礎，對於布居量與干涉態做微擾的展開，傳統的干涉態皆將起始的相位設為零。此處我們探討不同的起始相位對於布居量與干涉態的影響。

The thesis is about computational chemistry, which contents static quantum chemistry calculation base on electronic structure theory, and the dynamics of open quantum system by dealing the elements of density matrix with perturbation theory. For the part of quantum chemistry, we study the intermolecular interaction by using wave function theory(WFT) and density functional theory(DFT) by using Gaussian 09 suite of program package. Acrylamide monomers and dimers are studied to investigate the hydrogen bonding effect on the structures and the infrared spectral shifting. The formamide-formamide, formamide-formic acid and formic acid-formic acid dimeric complexes are selected to explore the mechanism of double proton transfer (DPT) reactions, the reaction mechanism is elucidated by examining the reaction force, the chemical potential and the reaction electronic flux. On the other hand, the specific intermolecular interaction, halogen bonded system, are also studied. The bond strength, bond distances change, and the infrared spectral shifting are analysis by the σ-hole model. As the part of quantum dynamics, a perturbation theory is developed to obtain the explicit time evolution for quantum coherence. The decoherence dynamics is drawn by assuming the different interaction strength of the perturbed Hamiltonian on population and coherence. New patterns of oscillation for the quantum phases of a generic quantum system are observed and discussed. This treatment provided a new avenue to study the decoherence dynamics.