中国物理B ›› 2013, Vol. 22 ›› Issue (2): 23301-023301.doi: 10.1088/1674-1056/22/2/023301

• ATOMIC AND MOLECULAR PHYSICS • 上一篇    下一篇

Quantum chemical calculations of bond dissociation energies for COOH scission and electronic structure in some acids

曾晖, 赵俊, 肖循   

  1. College of Physical Science and Technology, Yangtze University, Jingzhou 434023, China
  • 收稿日期:2012-05-28 修回日期:2012-08-07 出版日期:2013-01-01 发布日期:2013-01-01
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 11047176) and the Research Foundation of Education Bureau of Hubei Province, China (Grant Nos. Q20111305, B20101303, T201204, B20111304, and Q20091215).

Quantum chemical calculations of bond dissociation energies for COOH scission and electronic structure in some acids

Zeng Hui (曾晖), Zhao Jun (赵俊), Xiao Xun (肖循)   

  1. College of Physical Science and Technology, Yangtze University, Jingzhou 434023, China
  • Received:2012-05-28 Revised:2012-08-07 Online:2013-01-01 Published:2013-01-01
  • Contact: Zhao Jun E-mail:zhaojun@yangtzeu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 11047176) and the Research Foundation of Education Bureau of Hubei Province, China (Grant Nos. Q20111305, B20101303, T201204, B20111304, and Q20091215).

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摘要： Quantum chemical calculations are performed to investigate the equilibrium C-COOH bond distances and the bond dissociation energies (BDEs) for 15 acids. These compounds are studied by utilizing the hybrid density functional theory (DFT) (B3LYP, B3PW91, B3P86, PBE1PBE) and the complete basis set (CBS-Q) method in conjunction with the 6-311G** basis as DFT methods have been found to have low basis sets sensitivity for small and medium molecules in our previous work. Comparisons between the computational results and the experimental values reveal that CBS-Q method, which can produce reasonable BDEs for some systems in our previous work, seems unable to predict accurate BDEs here. However, the B3P86 calculated results accord very well with the experimental values, within an average absolute errors of 2.3 kcal/mol. Thus, B3P86 method is suitable for computing the reliable BDEs of C-COOH bond for carboxylic acid compounds. In addition, the energy gaps between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of studied compounds are estimated, based on which the relative thermal stabilities of the studied acids are also discussed.

关键词: bond dissociation energy, density functional theory, CBS-Q method

Abstract: Quantum chemical calculations are performed to investigate the equilibrium C-COOH bond distances and the bond dissociation energies (BDEs) for 15 acids. These compounds are studied by utilizing the hybrid density functional theory (DFT) (B3LYP, B3PW91, B3P86, PBE1PBE) and the complete basis set (CBS-Q) method in conjunction with the 6-311G** basis as DFT methods have been found to have low basis sets sensitivity for small and medium molecules in our previous work. Comparisons between the computational results and the experimental values reveal that CBS-Q method, which can produce reasonable BDEs for some systems in our previous work, seems unable to predict accurate BDEs here. However, the B3P86 calculated results accord very well with the experimental values, within an average absolute errors of 2.3 kcal/mol. Thus, B3P86 method is suitable for computing the reliable BDEs of C-COOH bond for carboxylic acid compounds. In addition, the energy gaps between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of studied compounds are estimated, based on which the relative thermal stabilities of the studied acids are also discussed.

Key words: bond dissociation energy, density functional theory, CBS-Q method

中图分类号:  (Bond strengths, dissociation energies)

  • 33.15.Fm
31.15.A- (Ab initio calculations)