高等学校化学学报 ›› 2006, Vol. 27 ›› Issue (1): 96-99.

• 研究论文 • 上一篇    下一篇

LFMO和NBO的定域性和作用能解析

刘向文,包鹏,虞忠衡   

  1. 中国科学院化学研究所, 分子动态与稳态结构国家重点实验室 北京 100080
  • 收稿日期:2005-01-06 出版日期:2006-01-10 发布日期:2006-01-10
  • 通讯作者: 虞忠衡(1944年出生), 男, 博士, 研究员, 博士生导师, 从事物理有机化学研究. Email: yuzh@icas.ac.cn
  • 基金资助:

    国家自然科学基金(批准号: 20272063, 20472088)资助.

Localization Character of LFMO and NBO and Interaction Energy Analysis

LIU Xiang-Wen, BAO Peng, YU Zhong-Heng   

  1. State Key Laboratory of Stable and Unstable Species, Institute of Chemistry,Chinese Academy of Sciences, Beijing 100080, China
  • Received:2005-01-06 Online:2006-01-10 Published:2006-01-10
  • Contact: YU Zhong-Heng,E-mail: yuzh@icas.ac.cn

摘要:

为分析苯并分子C12H6的垂直共振能(VRE), 建立了定域片断分子轨道(LFMO)和自然键轨道(NBO)两种基组, 并在两种基组之上进行NBO能量分析和Morokuma能量分解. 在NBO能量分析中, 两种基组的VRE都是稳定的; 而在Morokuma能量分解中, VRE的稳定性取决于基组. 在NBO能量分析中, Fock矩阵的一次性对角化忽视了σ体系和π体系之间的电子耦合作用. 故NBO基组和NBO能量分析方法在计算VRE时似乎都不合理.

关键词: 自然键轨道; 定域片断分子轨道; 一次性对角化; Morokuma能量分解; 垂直共振能

Abstract:

To analyze the vertical resonance energy(VRE) of C12H6, the localized fragment molecular orbital(LFMO) and the natural bond orbital(NBO) basic sets are constructed. Then, the NBO and Morokuma′s SCF energetic analysis are performed over each of them. The VRE, obtained from the NBO electronic analysis, is always unstable. But the VRE, obtained from Morokuma′s SCF energy partition, depends on the basis set. In addition, the singly diagonalized process for the Fock matrix in the NBO energetic analysis ignores the electronic coupling between σ and π systems. In a word, the NBO basic set and its energetic analysis seems to be unreasonable as far as the calculation of VRE is concerned.

Key words: Natural bond orbital(NBO); Localized fragment molecular orbital(LFMO); Singly diagonalization; Morokuma′s SCF; Vertical resonance energy

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