物理化学学报 >> 2018, Vol. 34 >> Issue (3): 303-313.doi: 10.3866/PKU.WHXB201708302

所属专题: 密度泛函理论中的化学概念特刊

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从能量和信息理论视角理解单取代烷烃的异构化

钟爱国*(),李嵘嵘,洪琴,张杰,陈丹   

  • 收稿日期:2017-07-19 发布日期:2017-12-18
  • 通讯作者: 钟爱国 E-mail:zhongaiguo@tzc.edu.cn
  • 基金资助:
    浙江省自然科学基金(LY15B030001);浙江省自然科学基金(LY15B060001);浙江省大学生科技创新(2017R430014)

Understanding the Isomerization of Monosubstituted Alkanes from Energetic and Information-Theoretic Perspectives

Aiguo ZHONG*(),Rongrong LI,Qin HONG,Jie ZHANG,Dan CHEN   

  • Received:2017-07-19 Published:2017-12-18
  • Contact: Aiguo ZHONG E-mail:zhongaiguo@tzc.edu.cn
  • Supported by:
    the Natural Science Foundation of Zhejiang Province, China(LY15B030001);the Natural Science Foundation of Zhejiang Province, China(LY15B060001);Zhejiang Province Undergraduate Student Innovation Project, China(2017R430014)

摘要:

对直链烷烃和支链烷烃的相对稳定性统一的解释仍然没有定论,并且一直在进行着。以单取代的烷烃体系CnH2n+1―R (n = 3, 4, 5, 6;R = OH, OCH3, NH2, NO2, F, Cl, CN, CHO)为例,本文对支链效应的有效性和本质进行了研究。与传统的基于轨道的描述不同的是,本文采用了密度泛函理论的总能量和基于新能量分配方案的能量分量[见Liu, S. B. J. Chem. Phys. 2007, 126, 244103]。新型能量分解方法计算结果表明,静电效应和立体效应等对支链效应的存在都起着重要作用,但是它们均不能单独用来解释支链效应的本质。用双变量(静电势和空间位阻)组合,发现单取代烷烃衍生物的异构化反应主要影响因子是静电势作用,空间位阻效应的影响是次要的。此外还发现了香农熵差与Fisher信息差之间的线性关系,未能发现总能量差或者分能量差值和Fisher信息或者Shannon熵之间的关系。这与前人发现是一致的。

关键词: 分子稳定性, 空间位阻, 密度泛函理论, 能量分项

Abstract:

A unified explanation for the relative stability of linear and branched alkanes is still lacking, and research in this direction is ongoing. Unlike the conventional orbital-based description, we have employed the density functional theory (DFT) based on the total energy and its components as well as a newly proposed energy partitioning scheme [Liu, S. B. J. Chem. Phys. 2007, 126, 244103]. Taking monosubstituted hydrocarbons CnH2n+1―R (n = 3, 4, 5, 6; R = OH, OCH3, NH2, NO2, F, Cl, CN, CHO) as examples, we have investigated the molecular origin and nature within the framework of the DFT. Our computational results revealed that no such a single energy component that dictates the transformation of the mono-substituted alkane derivatives. By the binary fit of the electrostatic potential and steric hindrance from the new energy decomposition scheme, we unraveled that isomerization is mainly governed by the electrostatic potential, while the steric effect has a minor influence. Moreover, we established a linear relationship between the Shannon entropy difference and the Fisher information difference, which is accordance with previous findings. Further, there was no linear relationship between Ee and the Fisher information or Shannon entropy.

Key words: Molecular stability, Steric hindrance, Density functional theory, Energy component

MSC2000: 

  • O641