DNA电子结构与极化子传输的紧束缚方法研究

【作者】 郑斌；

【导师】 刘成卜；

【作者基本信息】 山东大学 ， 物理化学， 2006， 博士

【摘要】 DNA是生物界最重要的大分子体系，在生物进化中起着非常重要的作用，其结构中蕴藏着决定遗传、细胞分裂、分化、生长和蛋白质生物合成等生命过程的信息。近年来由于生命科学中的损伤与修复等原因以及分子纳米器件的应用与发展，DNA的电荷输运性质成为当前生命科学的一个研究热点。研究已初步发现，电荷转移反应产物能导致细胞突变，光诱导电荷转移氧化损伤DNA分子或光诱导电荷转移修复DNA分子可治疗肿瘤等。例如，当DNA分子受到电离辐射或紫外线照射时会产生电子，这个电子被别的原子捕获前可能沿着DNA分子链运动，所以有人认为DNA分子有可能是快速的，不依赖于距离的电子转移通道。因此，如果DNA具有导电性，将是纳米导线及分子器件的理想材料。但其电子转移机制目前尚不清楚，所以如何从理论上解释这一现象，弄清电子在DNA中的传输机理，为DNA的突变和修复规律提供理论解释，阐明DNA结构中蕴藏的生命过程的各种信息，是生命科学领域中的重要问题，相关研究的进展对认识生命体系及设计基因与蛋白药物特别是肿瘤治疗等方面具有重要的科学意义。 生物分子体系有两个特点，一是分子尺寸大，二是分子结构复杂。目前的理论化学方法对中等尺度以下的分子能够提供较精确的计算结果，但处理复杂的生物分子体系尚有困难。因此必须发展处理复杂生物体系的理论方法。 目前，关于材料性质的计算方法大致可分为两类：一类是ab initio方法，即所谓的“第一性原理”，该方法不需要借助任何经验的或实验的结论；另一类则是建立在已有的实验结果基础上的半经验(semiemperical)方法。ab initio方法主要被用于对新材料和结构复杂材料的分析，特别适用于对新材料性质的预测，从而在大范围内预见性地指出其各种可能的性质。而半经验的方法是在严格遵循现有材料性质的基础之上，外推得到同类材料的其他性质。第一原理是理论计算化学体系最根本的方法，但其效率太低，对于复杂化学体系相应的尺寸结构，目前的软硬件条件仍无法承担如此巨大的计算复杂度。与从头算方法相比，半经验方法作了很多近似处理，在计算中加了很多拟合参数，所以计更多还原

【Abstract】 DNA is the most important molecule of bioorganic system. Its structure contains information that determines heredity, cell division, growth and biosynthesis of protein. Interference with gene function and prevention of transcription and translation can kill invading microorganisms or tumour cells. In recent years, the charge migration along the duplex DNA stack is attracting considerable interest for the biochemical reasons in life science, as well as for the possible applications in molecular electronics. A number of experiments have showed that, the product of electron transfer will lead to DNA mutation, light-induced electron transfer will damage DNA, or repair it to cure tumour. For example, under the irradiation of the ionization or ultraviolet radiation, an electron in DNA will move along DNA before being traped by other atoms. So it is thought that DNA may be a quick channel for electron transfer which is independent of distance. Therefore, if DNA is a conductor, it will be the ideal material for nano-line and molecular electronics. At present, the mechanism of DNA electron transfer has been still a puzzle now. So how to explain these phenomena, ravel the mechanism of electron transfer, and explain theoretically the mutation and repair law for DNA, which are the most important problems in life science. Progress in related research has great meaning in the knowledge of biological system and the design of gene with protein drug, especially in the cancer therapy.The biology molecules DNA have two characters. One is the large size, the other is the complicated structure. The classical theoretical chemistry methods can offer relatively accurate results for middle-size molecules, but it is difficult for it to deal with the complicated biology molecules. So it is important to develop the theoretical chemistry methods for the complicated biology molecules.At present, there are two calculation methods for material properties. One is ab initio method, namely, First-principles. It does not need any experiential data. The other is the semi-empirical method, which is based on some existent experiment results. Ab initio method is the most essential theoretical method for chemistry更多还原