【作者】 沈颖；

【导师】 赵铧；

【作者基本信息】 重庆大学 ， 凝聚态物理， 2012， 硕士

【摘要】 1977年，科学家们发现，通过掺杂可以将聚乙炔的电导率极大的提高，变成良导体。从此以后，对导电聚乙炔的研究就引起了人们极大的兴趣。在导电聚合物的研究过程中，人们提出了一些新的观念，如二聚化、孤子、分数电荷等。同时，导电聚合物还是一类具有广阔应用前景的新材料，它不仅可塑性好，而且价格低廉，便于大量生产。目前，人们已经研制出各种各样的有机光电子器件，如发光二级管（LED），场效应管（FET），光伏电池等。为了这些器件的设计，需要我们去理解许多有关的微观过程，如光化学反应、光激发动力学以及能量和电荷的输运，而这些又涉及到电子-晶格耦合的动力学。在本学位论文中，我们主要研究了导电高分子中的极化子动力学性质。在我们的研究中，我们采用了扩展的SSH哈密顿模型,加入了长程电子关联哈密顿量，在自然边界条件下，利用绝热动力学方法研究了有限长反式聚乙炔链中平均关联能随时间的演化，计算了长程电子关联对极化子动力学的影响以及极化子状态下的长程电子关联能。从计算结果中我们发现，加入一个电子或一个空穴后，平均关联能的大小先随着时间呈非周期性阻尼振荡，在经过一定时间后，平均关联能趋近于一个恒定值，同时系统达到一个稳定的极化子位形。当格点数增加时，长程关联能趋于恒定的时间将逐渐缩短。第一章介绍了聚乙炔的结构。由于聚合物是链状结构，是准一维体系，它会出现一些新特征，如Peierls不稳定性，二聚化等。描述这种准一维体系的模型—Su-Scherieffer-Heeger模型，简称SSH模型。第二章介绍了聚合物中的元激发。在高聚物中，由于强的电子—晶格耦合作用，聚合物中的元激发是既包含电荷，又有晶格畸变的激发，如孤子，极化子，双极化子，在本章中，我们将讨论这些元激发的电荷分布和能带结构。第三章简单介绍了动力学模型与方法，并讨论了加入电子—电子相互作用带来的影响，再讨论加入长程电子关联项对系统产生的影响，以及长程电子关联能在不同情况下随时间的演化过程。第四章简述了一下有机高分子聚合物的应用前景。更多还原

【Abstract】 In1977, the scientists discovered that conductivity of polyacetylene becomes largewhen it was doped. It becomes good conductor from insulator. From then on, peoplewere interested in the conducting polyacetylene. In studying the conducting polymers,people put forward new concepts such as solitons and fractional charges. Theconducting polymers are a sort of new materials which have a broad prospect ofapplications. The conducting polymers have good plasticity. The cost price to buy ischeap. It is convenient for mass production of them. At present, people have developeda variety of organic optoelectronic devices, such as light emitting diode (LED), fieldeffect transistor (FET), photovoltaic cells.With design of these devices, we are required to understand many microscopicprocesses, such as photochemical reaction, photo-excitation dynamics, andenergy-charge transport, which are in turn related to the dynamics of electron-latticecoupling in the conducting polymers. In this dissertation, we mainly study dynamicproperties of polaron in conductive polymer. In studying, we adopt the extended SSHmodel plus the long-range correlation Hamiltonian and natural boundary condition. Wecalculate changes of the long-range correlation energy with time in a finite length oftrans-polyacetylene under adiabatic condition in terms of dynamic method and effect ofthe long-rang electron correlation on polaron dynamics. It is found from ourcomputational results that the long-rang correlation first shows a non-periodic dampedoscillation with time when we add an electron or a hole into the trans-polyacetylenechain and then after some time the long-rang correlation energy goes to a constant valueand at the same time the stable lattice configuration of the system is formed. The timethat the long-rang correlation energy tends to a constant will be shorter with increasinglattice numbers.Chapter1is introduction to the structure of polyacetylene. Polymer chain isquasi-one-dimensional system; it has many new features, such as the Peierls instability,dimerization. We adopt Su-Schrieffer-Heeger model to describe the one-dimensionalsystem. Chapter2is about the elementary excitations in polymers. These elementaryexcitations include soliton, polaron, and bipolaron. We discuss charge distribution andenergy level structure in the elementary excitations. Chapter3is about the dynamicmodel and method. We discuss long-range electron correlation effect and the evolution of long-range electron correlation in time in different situations. At last, we discuss theapplication prospects of organic polymers.更多还原