【作者】 王彦华；

【导师】 王传奎；

【作者基本信息】 山东师范大学 ， 原子与分子物理， 2003， 硕士

【摘要】 近几十年来，由于非线性光学材料在现代激光技术、光学通讯、数据储存、光信息处理等器件中的广泛应用及其诱人的应用前景，引起了科学家们对新型非线性光学材料研究的浓厚兴趣，其中，如何研制高效的非线性光学材料成为一项重要课题。由于有机非线性光学材料具有宽的响应波段、良好的柔韧性、高的光损伤阈值和较低成本，以及易于合成、可以进行裁减和修饰等特点而备受重视。 硝基苯胺(para-Nitroaniline)分子由于具有较强的非线性光学响应而受到理论工作者和实验工作者的广泛关注。但到目前为止，理论计算结果和实验测量结果符合得并不是很好。因此，本文以pNA分子作为研究对象，对该分子的非线性光学性质进行了更深入的研究。 本文在含时密度泛函理论基础上研究了汽相下pNA分子体系的非线性光学性质。首先在密度泛函理论基础上优化了汽相下pNA分子体系的几何结构。然后运用含时密度泛函理论及少态方法对pNA分子体系的非线性光学性质进行了理论研究。计算了二次谐波振荡过程和电光Pockels效应过程的一阶非线性超极化率，研究了电子的相关能对pNA分子的非线性光学性质的影响以及pNA分子的一阶非线性超极化率与外加光电场频率之间的色散关系，并着重讨论了量子化学从头计算中基矢组的选取对计算结果的影响。 本文还在含时密度泛函理论基础上着重研究了溶剂效应对pNA分子的非线性光学性质的影响。溶剂模型采用了极化连续模型。首先，在密度泛函理论基础上采用极化连续模型重新优化了pNA分子在每种溶剂中的几何结构，研究了不同溶剂对pNA分子的几何结构的影响。然后在含时密度泛函理论基础上采用极化连续模型和少态方法研究了不同溶剂中pNA分子的非线性光学性质，计算了二次谐波振荡过程的一阶非线性超极化率，并讨论了pNA分子的非线性光学性质与溶剂极性之间的关系。研究发现pNA分子的非线性光学性质与溶剂极性之间的关系并不是单调的。这一结论不同于以往的理论研究结果。 硕士学位论文 中文摘要 本文还就氢键的形成以及原子核的振动对 pNA分子的非线性光学性质的影响进厅了初步探讨。研究发现氢键对 pNA分子的非线性光学性质的影响比较大，而零点振动平均对pNA分于的一阶非线性超极化率的贡献并不很明显。 整篇论文分为五章。第一章为综述，简单介绍了线性光学和非线性光学以及非线性光学性质的研究现状。第二章非线性光学性质，首先分别从宏观和微观两个角度讨论了极化强度和电偶极矩与外加光电场强度之间的关系，同时给出了线性极化率和非线性超极化率的定义，然后分别运用含时微扰理论和密度矩阵理论求解了分子体系的线性极化率和非线性超极化率。第三章就近年来发展起来的基于量子化学从头计算法的几种计算非线性光学性质的方法作了简单介绍。第四章介绍了本论文的研究过程和计算结果，并与已有的理论计算结果和实验测量结果进行了比较。第五章给出了本文的主要研究结论。更多还原

【Abstract】 In the last few decades, scientists have shown great interest in the study of new nonlinear optical materials, due to their widely use and attractive application foreground, for instance, in modern laser technology, optical communication, data storage, optical information processing, and other fields. It has become an important project to find new nonlinear optical materials of high efficiency. Much emphasis has been put on organic nonlinear optical materials because they have many advantages, such as wide response wave band, good flexibility, high optical damage threshold, low cost, and easy combination and modification.Much attention has been shown to Para-nitroaniline (pNA) for its strong nonlinear optical response. However, up to now, the theoretical results and the experimental ones do not agree very well. In this thesis, the nonlinear optical properties of pNA molecule are thoroughly studied.The nonlinear optical properties of pNA molecule in gas phase are studied on the base of time dependent density functional theory. First, the geometry of PNA molecule in gas phase is optimized on the base of density functional theory. Then, the nonlinear optical properties of pNA molecule are studied by using time dependent density functional theory and few states approach. The first order nonlinear hyperpolarizabilities in second-harmonic generation process and electro-optical pockels effect are computed. The basis set effects in ab-mitio quantum-chemical computation are mainly studied. The correction to the nonlinear optical properties due to the electronic correlation energy is discussed and the relationship between the first order hyperpolarizabilities and the frequencies of the external electric field is also investigated.The solvent effects on the nonlinear optical properties of PNA molecule are also chiefly studied on the base of time dependent density functional theory. The polarized continuum model is used to simulate the influence of the solvent environment on the solute molecule. In the first place, the geometry optimization of pNA molecule in each solvent is redo by usingthe polarized continuum model on the base of density functional theory. Secondly, the nonlinear optical properties with pNA molecule in different solvents are studied through using the polarized continuum model and few states approach on the base of time dependent density functional theory, and the first order nonlinear hyperpolarizabilities in second harmonic generation process are computed. It is found that the relationship between the nonlinear optical properties and the polarities of the solvents is non-monotonic, which is quite different from the previous conclusions.The hydrogen bonding effects and vibrational effects on the nonlinear optical properties are also investigated in this thesis. And it is found that the hydrogen bonding effects are quite important while the vibrational ones are not that obvious.The content of this thesis is as follows. The first chapter gives a brief introduction of linear and nonlinear optics and also the developing situation of the nonlinear optical properties. In the second chapter, the nonlinear optical properties are described from both macroscopic and microscopic views, at the same time, giving the definitions of the linear and nonlinear polarizabilities. Then, the explicit expressions of the linear and nonlinear polarizabilities are obtained by using quantum mechanical perturbation theory and density matrix formalism, respectively. The different approaches developed recently for calculating molecular nonlinear optical properties are summarized in chapter three. In the fourth chapter, the research process and the results are given in detail. The main conclusions are given in the last chapter.更多还原