高等学校化学学报

高等学校化学学报

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DFT能量分解和氮苄叉基苯胺分子π电子离域能的研究

马艳平, 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:2005-08-17 修回日期:1900-01-01 出版日期:2006-08-10 发布日期:2006-08-10
  • 通讯作者: 虞忠衡

Separation of DFT Energy and the Study on π-ElectronDelocalization Energy in Benzylideneaniline

MA Yan-Ping, 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:2005-08-17 Revised:1900-01-01 Online:2006-08-10 Published:2006-08-10
  • Contact: YU Zhong-Heng

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摘要： 为了探索密度泛函理论(DFT)方法中氮苄叉基苯胺分子π电子离域的本质, 介绍了将非平面分子氮苄叉基苯胺分子的DFT能量分成π和σ的方法, 并将π和σ电子能量分成单电子能部分: 动能ΔEπK(θ), ΔEσK(θ)和位能ΔEπP(θ), ΔEσP(θ); 双电子相互作用部分: 库仑作用ΔEππJ(θ), ΔEσσJ(θ), ΔEπσJ(θ)和交换相关作用ΔEππXC(θ), ΔEσσXC(Δ)以及ΔEπσXC(θ), 分析了垂直离域能ΔEV的稳定性及π电子离域对π和σ体系的影响. 在B3LYP/6-31G*, 6-311G*, 6-31G(2d), 6-311G(2d)水平下的计算结果表明, 与经典观点不同, π电子的离域是失稳定的, 且平面时失稳定性最强; 分析各个能量分量表明, 在π电子的离域过程中, π和σ体系均对基组较敏感, π体系本身单电子能的影响大于σ体系, π电子离域对双电子部分作用的影响主要体现在π-σ的耦合作用上.

关键词: 密度泛函能量分解, π电子离域, 氮苄叉基苯胺

Abstract: Köster's method for separating the DFT energy of benzene into π and σ parts is used to investigate the nature of the π delocalization energy in a nonplanar molecule benzylideneaniline(NBA). Contrary to the classical viewpoints, the vertical resonance energy ΔEV is always destabilizing, and it is most destabilizing at about θ=0° geometry at B3LYP/6-31G*, 6-311G*, 6-31G(2d), 6-311G(2d) levels. Besides, the one electron energy of the π system is more sensitive to π delocalization than that of the σ system. Furthermore, it is the electronic coupling between the π and σ electrons, rather than the π-π and σ-σ interaction, that plays a main role in determining Coulomb and the exchange-correlation energy effects associated with the π interaction between fragments.

Key words: Energy Separation of DFT, π-Electron delocalization, Benzylideneaniline

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