Messengers在氫鍵團簇中扮演重要性之理論研究:評估及應用

Abstract

本論文中我們探討訊息攜帶氣體(messenger) 對於氫鍵團簇本身所造成的影響. 首先, 我們使用量子化學軟體計算質子化水二聚體及四種不同訊息攜 帶氣體(messenger) 系統, 其中包含穩定與過渡態結構, 鍵結能量, 以及穩定結構之游離趨勢曲線. 在使用不同的密度泛函近似下, 從評估結果中顯示, 長程修正混合泛函(long-range corrected hybrid functional) 與長程修正雙混成泛函(long-range corrected double hybrid functional) 對於質子化水二聚體與訊息攜帶氣體(Messenger) 系統中鍵結能量與游離趨勢曲線皆有不錯的表現. 其次, 我們使用簡諧振子近似法(harmonic superposition approximation) 與密度泛函理論(density functional theory) 來計算質子化甲醇團簇(H+(CH3OH)7) 的熱力學性質, 並模擬在有限溫度下訊息攜帶氣體(messenger) 的穩定性與質子化甲醇團簇的紅外線光譜. 從模擬的結果顯示, 在質子化甲醇團簇中加入訊息攜帶氣體 (messenger), 會使質子化甲醇團簇本身結構發生變化, 並使其氫鍵團簇由較為開放的異構體(如線性形狀, 單環) 逐漸摺疊(folding) 成較為緊密(雙環) 的型態.

The effect of messenger in the hydrogen bonded cluster was studied. First, we use quantum chemistry package to calculate the protonated water dimer(H+(H2O)2) and four kinds of messenger complex including the stable and transition state structure, interaction energy between H+(H2O)2 and messenger, and the dissociation energy curve. From the results of assessment among various density functionals, we found that the long-range corrected hybrid functional and long-range corrected double hybrid functional have more accuracy for describing the interaction energy and dissociation curve of the tagged messenger. Furthermore, we use the harmonic superposition approximation and density functional theory to calculate the thermodynamics properties of protonated methanol cluster(H+(CH3OH)7) and simulate the stability of messenger and infrared(IR) spectra of H+(CH3OH)7 in finite temperature condition. As a result, the temperature dependent IR simulation spectra show that the spectral change by the tagged messenger(Ne/Ar) is accounted for the the isomer switching, which corresponds to folding of the hydrogen bonded network from the open isomer to the compact isomer.