分子晶体及范德华团簇红外光谱的理论研究及集体振动模式的分析

发布时间：2018-12-07 19:39

【摘要】：量子化学第一性原理计算,尤其是密度泛函理论,随着超级计算机等硬件的飞速发展以及数值方法的不断改进,在材料科学和纳米技术等领域得到了广阔的应用。理论模拟为实验科学提供了大量的补充、分析和机理的解释。然而,分子间弱相互作用的理论模拟仍然是一个挑战性课题。人们在近年来通过理论推导和实验数据的结合发展了一系列精确模拟分子间相互作用力的新方法,使得我们可以开展相关体系的研究。本文基于密度泛函理论方法,模拟研究分子晶体、表面吸附、多聚体的结构和红外光谱,并分析分子间相互作用力对物质性质的影响。全文由以下各章组成:第一章简要介绍了密度泛函理论和分子间作用力。密度泛函理论的介绍包括了理论的提出、模拟真实体系的交换相关能量泛函的发展、用于结构优化的理论方法和分析物质振动特征的密度泛函微扰理论。分子间作用力介绍了几种相互作用及举例,及其在分子晶体中的作用和影响。本章最后介绍了论文中使用的几种计算软件。第二章进行了苯胺晶体集合振动模式的模拟和其红外光谱的分析,从而对分子间相互作用在分子晶体的影响展开研究。我们发现分子间作用力不仅使得某些红外振动模式发生比较大的频率位移和吸收峰强度的变化,而且还诱发了一些晶体内长程离域的集体振动模式。为了比较上述苯胺晶体的计算结果,我们在第三章模拟研究了苯胺多聚体范德华团簇和乙酰苯胺晶体。通过对它们红外振动模式的分析和讨论,我们发现了与苯胺晶体相似的比较大的频率位移和吸收峰强度的变化,但没有发现由分子间作用力引发的集体振动模式。从而揭示在分子间相互作用影响下,苯胺晶体中特殊的氢原子链式结构是导致长程离域集合振动模式的关键。第四章研究不同氧化亚铜晶面对铅离子的不同吸附性质。通过对几种氧化亚铜晶面的几何结构和吸附能的理论模拟分析和与实验结果的比较,找出在实际中吸附性能最优的材料。第五章对本文进行了总结,并对未来的发展提出了展望。
[Abstract]:With the rapid development of hardware such as supercomputers and the continuous improvement of numerical methods, first-principles calculations of quantum chemistry, especially density functional theory (DFT), have been widely applied in materials science and nanotechnology. Theoretical simulation provides a great deal of supplement, analysis and explanation of mechanism for experimental science. However, the theoretical simulation of weak intermolecular interactions remains a challenging topic. In recent years, a series of new methods to simulate the interaction between molecules have been developed through the combination of theoretical derivation and experimental data, which makes it possible for us to study the related systems. Based on density functional theory (DFT), the structure and infrared spectra of molecular crystals, surface adsorption, polymer structures and infrared spectra are simulated and the effects of intermolecular interactions on the properties of materials are analyzed. The thesis consists of the following chapters: chapter 1 briefly introduces the density functional theory and intermolecular forces. The introduction of density functional theory (DFT) includes the development of theory, the development of exchange-related energy Functionals for simulating real systems, the theoretical methods for structural optimization and the DFT theory for analyzing the vibration characteristics of matter. Several kinds of interactions and examples are introduced, and their effects in molecular crystals are also discussed. At the end of this chapter, several kinds of computing software used in this paper are introduced. In the second chapter, the vibration modes of aniline crystals are simulated and their infrared spectra are analyzed, and the effect of intermolecular interaction on molecular crystals is studied. It is found that the intermolecular force not only causes some infrared vibration modes to change greatly in frequency displacement and absorption peak intensity, but also induces some collective vibration modes in the long range delocalization of crystals. In order to compare the calculated results of aniline crystals, we simulated the aniline polymer van der Waals cluster and acetanilide crystals in chapter 3. Through the analysis and discussion of their infrared vibrational modes, we find the relatively large frequency shifts and absorption peak intensity changes similar to those of aniline crystals, but no collective vibration modes induced by intermolecular forces are found. It is thus revealed that the special chain structure of hydrogen atoms in aniline crystal is the key to the long range delocalized collective vibration mode under the influence of intermolecular interaction. In chapter 4, the adsorption properties of different cuprous oxide on lead ions were studied. Through the theoretical simulation and comparison with the experimental results of the geometrical structure and adsorption energy of several kinds of cuprous oxide crystal planes, the materials with the best adsorption performance in practice are found out. The fifth chapter summarizes this paper and puts forward the prospect of the future development.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O641.121

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