【作者】 王笑楠；

【导师】 杨忠志；

【作者基本信息】 辽宁师范大学 ， 物理化学， 2006， 硕士

【摘要】 依据密度泛函理论，体系的电子密度决定了体系的一切性质，因此准确计算分子体系的电荷分布对解释和预测它的结构和性质具有重要作用。由于传统的从头算方法所需计算量大，对于大的分子体系非常耗时。因此，发展准确的、计算上易于实行的方法用于探讨大分子的性质是现在理论化学的重要任务。我们以密度泛函理论和电负性均衡原理为基础，建立和发展了原子-键电负性均衡方法中的σπ模型(ABEEMσπ)。本文应用该模型计算了氨基酸二肽和致癌性胺离子反应过程中的电荷分布，并对结果进行了讨论。结果表明，所计算出的电荷可以和从头算结果很好地相关联，并且对于致癌性胺离子反应过程中的电荷变化与实验中测量的化学位移的结果相对应，而与从头算方法相比计算所需要的时间大大缩短。由此可见，原子-键电负性均衡方法中的σπ模型可以推广应用到研究反应中。更多还原

【Abstract】 According to density functional theory, the electron density of a system determines all properties of the system. So accurate calculation of charge distributions in a molecular system plays an important role in explaining and predicting its structure and properties. Conventional ab initio methods are hard to apply to large molecular systems, because it spends much time. Hence, developing an accurate and economic method to probe the properties of large molecules is a promising research area in current theoretical chemistry. We have built and developed an atom-bond electron-egativity equalization σπ model (ABEEMσπ) on the basis of density functional theory and electronegativity equalization principle. Using ABEEM σπ, charge distributions of amino-acid dipeptide and nitrenium ions reaction are calculated. The results of calculation may be well relevant to those of ab initio method. Compared to ab initio method it is timesaving. Especially in the reaction of nitrenium ions, charges which transfer in the reaction is corresponding to the chemical shift. As a result, ABEEMσπ has a widespread prospect in developing and applying to the systems of reaction.更多还原