分子體系中Intracule電子相對密度分布的理論計算與系統研究

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Title:	分子體系中Intracule電子相對密度分布的理論計算與系統研究
Other Titles:	Systematic Studies and Theoretical Calculations on Electron Intracule and Extracule Densities of Molecular Systems
Authors:	劉光華
Contributors:	行政院國家科學委員會東海大學化學系
Date:	2009
Issue Date:	2011-07-25T01:10:30Z (UTC)
Abstract:	(一)分子體系中Intracule電子相對密度分佈的理論計算與系統研究電子——電子相對坐標空間的電子對密度分佈(electron intracule density)與相對於電子對坐標中心的電子密度分佈(electron extracule density)不同於通常意義下相對於核坐標的電子密度分佈﹐儘管它們之間有一定的聯繫。前者包含了所有的電子相互作用信息﹐其系統計算與研究將有助於認識不同分子中化學鍵的本質。 (二) 標準分子生成熱焓的半經驗計算利用分子自洽場計算後的電子密度分佈與Bader的分子中原子概念(Bader's AIM)﹐根據以往的研究成果(包括已發表和未發表的)﹐建立一個簡單?合理而有效的半經驗模型﹐對一系列有機分子以及一般分子的標準生成焓進行較精確的估算。 (三) 定域化的Kohn-Sham分子軌道密度泛函理論中的 Kohn-Sham分子軌道一般都是很離域化的﹐其中各原子的貢獻一般很分散﹐不利於分析原子間相互作用與化學鍵的性質。而分子軌道硬度矩陣的對角化可以產生定域化的Kohn-Sham分子軌道﹐其形式與特點值得研究。同樣﹐一些基本概念與規則﹐比如軟硬酸鹼定律﹐最大化學硬度原理等等﹐也一直是我們感興趣的研究課題。其中一些還尚存一定爭議。 (四) 量子化學計算的一些具體應用利用量子化學計算程式對一些含硅自由基離子在氣態與液相中的不同反應機理進行計算與研究。 My researches have been focused mainly on two aspects: one is the development of some basic concepts, principles and methods in theoretical chemistry; the other is the application of computational chemistry methods to chemical systems in gas phase and solution. In particular, some of my research interests are as follows: 1) Systematic Studies and Theoretical Calculations on Electron Intracule and Extracule Densities of Molecular Systems We have developed methods to accurately calculate electron intracule density - the electron density distribution in the inter-electron coordinate space, and extracule density – the electron density in the center-of-electron pair coordinate space. They have shown different electron density distributions and patterns from the usual electron density in the nuclear coordinate space. The continued researches on this aspect would be helpful on understanding the nature of electron interaction and chemical bonds. 2) Developing semi-empirical density-functional methods to estimate standard heats of formation of molecules After a regular Hartree-Fock and/or density-functional SCF calculation, we may utilize some post SCF properties such as bond-distances, electron densities at bond-critical points, etc., to fit sets of accurate known experimental data to develop new semi-empirical density-functionals to calculate molecular energies and standard heats-of-formation (enthalpies) accurately yet at low cost. 3) Using computational chemistry methods to study electronic structures and chemical reaction mechanisms Using computational chemistry methods, for example, density functional methods, such as B3LYP, and more recent M05-L and M06-L families, to study the reaction mechanisms of cation radicals in gas phase and solution. A more challenging problem is the accurate energy calculation of molecular systems with large inter-atomic distances. 4) Hard-soft acid principle and maximum hardness principle: I have been interested in the study of some basic concepts and principles, though some of them are controversial. There has been a Chinese saying: “A substance tends to go with its like.”(物以?聚) Hard-soft acid and base principle and maximum hardness principle are two empirical principles summarized from observation of some chemical phenomena. The former was known to me since I studied chemistry textbooks in high school. We have been trying to show them from the first principle in the framework of density functional theory. Furthermore, we analyze the scopes and conditions of these principles. Related are electronegativity equalization principle, orbital/fragmental hardness and softness, Fukui indices, frontier orbitals, and localized Kohn-Shan orbitals.
Relation:	研究編號：NSC98-2113-M029-001 研究期間：2009-02~ 2010-07
Appears in Collections:	[化學系所] 國科會研究報告

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