利用 wave-function based theory和 density functional theory (DFT) 來研究 CO 和 Pt/Pt2 金屬之間的作用力

Theoretical Studies of The Interaction Between CO And Pt/Pt2 Cluster by Using Wave-Function Based Theory And Density Functional Theory

林為心(Uei-Shin Lin)

指導教授 ： 李錫隆

國立中正大學/理學院/化學暨生物化學系/碩士(2014年)

摘要

本論文主要是利用 wave-function based theory和 density functional theory (DFT) 來研究 CO 和 Pt/Pt2 金屬之間的作用力。我們發現 HF 方法所預測之 PtCO 的結合能最低；而使用 PBE 和 PW91 方法則預測出最高的結合能 (3.7 eV)。此外，隨著 DFT 方法中所混入之 HF exchange 的比例增加，所預測之 PtCO 的結合能亦會降低。另一方面，當 CO 鍵結在 Pt2 上時，大多數方法所預測之最穩定的結構皆為橋狀 Pt2CO。結合能的預測方面，MP2 方法所預測的結合能最高；而 PBE 和 PW91 方法預測的結合能則與 CCSD(T) 極為相近 (3.1 eV)；隨著 DFT 方法中所混入之 HF exchange 的比例增加，Pt2CO 的結合能亦會下降。本研究亦進一步利用化學鍵結分析來探討不同的方法對於 CO 鍵結行為預測的差異，並分析 CO 和 Pt/Pt2 之間的鍵結情形。

關鍵字

密度泛函理論 ； 作用力 ； 鉑 ； 一氧化碳 ； 電荷分析

並列摘要

In this study, the interactions between CO and Pt/Pt2 clusters were investigated by using the wave-function based methods, HF, MP2 and CCSD(T), and density functional theory, PBE, PW91, B3LYP, M06-2X, and M06-HF. For the interaction between CO and Pt, it is found that the HF method predicts quite low binding energy of -0.74 eV. For GGA functional, the PBE and PW91 give stronger binding energies of ca. 3.7 eV comparing with other methods. For hybrid DFT, the binding energy for B3LYP is -2.93, closed to that for CCSD(T). When adding the more contribution of HF exchange in functional, it is found that the binding energy become weaker. For CO binding on Pt2, all methods predict the stable structure is singlet bridge structure of Pt2CO except HF method. The MP2 method predicts quite strong binding energy of -4.42 eV. For GGA functional, both the PBE and PW91 give stronger binding energies of ca. 3.1 eV comparing with other DFT methods, closed to that for CCSD(T). For hybrid DFT, when adding the more contribution of HF exchange in functional, it is found that the binding energy become weaker. The chemical bonding analysis is also considered to check the different between HF and DFT methods in predicting the binding behavior.

並列關鍵字

B3LYP ； PW91 ； PBE ； chemical bonding analysis ； binding energy ； density functional theory (DFT) ； wave-function based theory ； Pt/Pt2 ； CO ； M06-2X ； M06-HF ； HF ； MP2 ； CCSD(T)

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