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標題: | 甲烷分子與水分子之量子化學勢能計算與分子動力學模擬 Quantum Chemistry Calculated Intermolecular Interaction and Molecular Dynamics Simulation of Water and Methane |
作者: | Yu-De Chen 陳育德 |
指導教授: | 趙聖德(Sheng-Der Chao) |
關鍵字: | 甲烷-水分子二聚體,水分子二聚體,Hartree-Fock(HF)近似法,Mø,ller-Plesset(MP)微擾理論,耦合簇理論(CC),密度泛函理論(DFT),分子動力學模擬,徑向分佈函數(RDF),速度自相關函數(VAF),擴散係數, methane-water dimer,water-water dimer,Hartree-Fock (HF) Approximation,Mø,ller-Plesset (MP) perturbation theory,density functional theory (DFT),coupled cluster(CC) method,Molecular Dynamics simulation,radial distribution function (RDF),Velocity Autocorrelation Function (vaf),Diffusion Constant, |
出版年 : | 2011 |
學位: | 碩士 |
摘要: | 我們使用MP2/aug-cc-PVQZ計算甲烷分子與水分子的單體最佳化結構,以自洽理論(Hartree-Fock,HF)、微擾理論(Møller-Plesset perturbation theory,MP)、密度泛函理論(Density Functional Theory,DFT)及耦合簇理論(Coupled Cluster Method,CC)等四種量子化學理論以進行甲烷-水分子及水分子二聚體之間的分子作用力計算,且均加入了BSSE修正。其中,HF計算了排斥力、靜電力以及感應電磁力,而MP2則是計算出完整的位勢能曲線,接著再使用大範圍exchange-correlation functional 的配對並輔以基底函數aug-cc-PVTZ進行DFT的計算,並將計算結果與MP2加以比較。另外,我們分析以不同基底函數計算所得到的結果,並計算其基底極限值(basis set limit)。
在完成量子化學計算後,我們使用修正過的TIP4P模型(TIP4P(M))擬合量子化學計算得到的水分子二聚體勢能曲線,並建構出力場,將其代入牛頓方程式進行分子動力學模擬,藉以得到水的平衡性質及動態性質,並與實驗值以及現有的文獻比較。另外,對水的模擬我們從三相點沿著氣化曲線計算至臨界點,模擬了不同溫度與密度下的徑向分佈函數(Radial Distribution Function,RDF)、速度自相關函數(Velocity Autocorrelation Function,VAF)與擴散係數(Diffusion constant)等,皆有相當不錯的準確度,這說明了以量子化學計算出的勢能曲線所建構出的力場來進行分子動力學模擬在實用性上亦有一定的可靠度。 We have optimized the structures of methane monomer and water monomer at MP2/aug-cc-PVQZ, and also calculated the intermolecular interaction potentials of the methane-water dimer and water-water dimer using the Hartree-Fock self-consistent theory(HF)、correlation-corrected second-order Møller-Plesset perturbation theory(MP2)、density functional theory(DFT) and coupled cluster(CC) method, and the correction of the basis-set superposition error(BSSE) has been included. The HF calculation yields repulsion, electrostatics and induction energies, and the MP2 calculation shows complete molecular interaction potentials. Then we have carried out the DFT calculations by eighty combinations of exchange-correlation functional and compare with the result of MP2. In addition, we have found that the basis set effect are significant, and calculated the complete basis limit. After the calculation of potential energy surface is completed, we choose TIP4P modified model (TIP4P(M)) to fit the ab initio data. Then we construct the force field by the parameters we found, and perform the molecular dynamics simulation from its triple point to the critical point along the gasification curve with different temperatures and corresponding densities. In addition, we compare the equilibrium and dynamic properties with the experiment data and previous investigations. The comparison of the radial distribution function (RDF), velocity autocorrelation function(VAF) and diffusion constant is acceptable. It shows that using the result of quantum chemistry computation to construct the force field can accurately reproduce the thermal properties. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/48036 |
全文授權: | 有償授權 |
顯示於系所單位: | 應用力學研究所 |
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