物理化学学报 >> 2014, Vol. 30 >> Issue (8): 1437-1446.doi: 10.3866/PKU.WHXB201405292

理论与计算化学 上一篇    下一篇

烷烃客体分子(CnHm, n≤6, m≤14)在51262和51264水笼中的稳定性与拉曼光谱的密度泛函理论计算

曹潇潇1, 苏艳1, 赵纪军1, 刘昌岭2,3, 周潘旺4   

  1. 1. 大连理工大学, 三束材料改性教育部重点实验室, 辽宁大连 116024;
    2. 国土资源部海洋油气资源与环境地质重点实验室, 山东青岛 266071;
    3. 青岛海洋地质研究所, 山东青岛 266071;
    4. 中国科学院大连化学物理研究所, 分子反应动力学国家重点实验室, 辽宁大连 116024
  • 收稿日期:2014-04-21 修回日期:2014-05-27 发布日期:2014-07-18
  • 通讯作者: 苏艳 E-mail:su.yan@dlut.edu.cn
  • 基金资助:

    国家自然科学基金（11174045，11304030）和中央高校基本科研业务费专项资金（DUT14LK19）资助项目

Stability and Raman Spectroscopy of Alkane Guest Molecules (CnHm, n≤6, m≤14) in 51262 and 51264 Water Cavities by Density Functional Theory Calculations

CAO Xiao-Xiao1, SU Yan1, ZHAO Ji-Jun1, LIU Chang-Ling2,3, ZHOU Pan-Wang4   

  1. 1. Laboratory of Materials Modification by Laser, Ion and Electron Beams of the Ministry of Education, Dalian University of Technology, Dalian 116024, Liaoning Province, P. R. China;
    2. Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology, Ministry of Land and Resources, Qingdao 266071, Shandong Province, P. R. China;
    3. Qingdao Institute of Marine Geology, Qingdao 266071, Shandong Province, P. R. China;
    4. State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116024, Liaoning Province, P. R. China
  • Received:2014-04-21 Revised:2014-05-27 Published:2014-07-18
  • Contact: SU Yan E-mail:su.yan@dlut.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (11174045, 11304030) and Fundamental Research Funds for the Central Universities of China (DUT14LK19).

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摘要：

可燃冰矿藏中气体成分非常复杂，通过谱学分析对水合物样品成分进行指认具有重要意义.基于B97-D/6-311++G（2d，2p）的密度泛函理论（DFT）计算，我们系统地探索了构成水合物的两种标准水笼（51262和51264）包络十八种不同烷烃客体分子的稳定性. 从计算结果可以看出，除了3-甲基戊烷和2，3-二甲基丁烷两个烷烃客体分子，其它16个烷烃客体分子都可以被容纳在51262笼中；但是与51262笼不同，十八种烷烃客体分子都可以被容纳在尺寸较大的51264笼中. 同时，我们也模拟了五种直链烷烃和四种环状烷烃在51262和51264笼中相应的谱学特征，从拉曼谱图上可以看出，随着碳原子数量的增多，直链烷烃客体分子C―H键伸缩振动区的多数拉曼谱带向高波数移动，而环状烷烃客体分子C―H键伸缩振动区的拉曼谱带则向低波数移动. 这些结果为实验上通过拉曼谱测量指认水合物矿藏的成分提供理论参考.

关键词: 密度泛函理论计算, 水合物, 烷烃, 稳定性, 拉曼光谱

Abstract:

The gas composition in natural gas hydrate deposits is complex, and therefore the use of spectroscopic analysis to elucidate the chemical composition is of great significance. Using density functional theory (DFT) calculations at the B97-D/6-311++G(2d, 2p) level, we systematically explored the stability of 18 alkane guest molecules in two standard water cavities (51262 and 51264). The results indicated that most alkane guest molecules can be stored in the 51262 cage, with the exception of 3-methylpentane and 2,3-dimethylbutane, while all 18 alkanes can be encapsulated in the 51264 cage. The Raman spectroscopic characteristics of five straight-chain and four cyclic alkane guest molecules in the 51262 and 51264 cages were also simulated. The majority of the Raman bands of the straight-chain alkanes in the C―H stretching region were found to move to higher wavenumbers as the number of carbon atoms increased, while most bands of the cyclic molecules in this region transitioned to lower wavenumbers. These theoretical results should prove helpful with regard to identifying hydrate deposits from experimental Raman spectroscopic data.

Key words: Density functional theory calculation, Hydrate, Alkane, Stability, Raman spectrum