【作者】 胡伟；

【导师】 杨金龙；

【作者基本信息】 中国科学技术大学 ， 物理化学， 2013， 博士

【摘要】 纳米材料是一种处于纳米量级的新一代材料,具有多种奇异的特性,展现特异的光、电、磁、热、力学、机械等物理化学性能,这使得纳米技术迅速地渗透到各个研究领域,引起了国内外众多的物理学家、化学家和材料学家的广泛关注,也成为当前世界最热门的科学研究热点。物理学家对纳米材料感兴趣是因为它具有独特的电磁性质,化学家是因为它的化学活性以及潜在的应用价值,材料学家所感兴趣的是它的硬度、强度和弹性。毫无疑问,基于纳米材料的纳米科技必将对当今世界的经济发展和社会进步产生重要的影响。因此,对纳米材料的科学研究具有非常重要的意义。其中,碳纳米材料是最热门的科学研究材料之一。我们知道,碳元素是自然界中存在的最重要的元素之一,具有sp、sp2、spa等多种轨道杂化特性。因此,以碳为基础的纳米材料是多种多样的,包括常见的石墨和金刚石,还包括近几年比较热门的碳纳米管、碳纳米线、富勒烯和石墨烯等新型碳纳米材料。最近,具有石墨烯类似结构的单层硅,也被称为硅烯,也被理论预测和实验合成所证实,也许成为最新的热门纳米研究材料。另外,最近几十年来,随着基于计算机的科学技术的日新月异的快速发展,使得基于密度泛函理论的第一性原理方法的相关理论基础和数值计算算法也取得了很多重大的研究进展和应用前景,尤其是在纳米材料科学中取得了重要的研究成果,已经在国内外引起了广泛关注。在本文中,我们主要利用第一性原理方法来研究和计算新型碳纳米材料的电子结构性质及其可能的实际应用。在第一章中,我们简单地介绍了密度泛函理论的基本知识,主要包括Hartree-Fock方程、Kohn-Sham方程和密度泛函理论的核心问题：交换相关能量泛函。最后,我们还介绍了常见的基于密度泛函理论的计算软件包。在第二章中,我们主要利用第一性原理计算来研究基于金刚石的纳米材料中掺杂NV色心的结构和电磁性质,并结合电偶层模型来模拟和解释金刚石纳米材料的表面化学修饰和尺寸大小对两种不同NV色心(NV0和NV-)的相对稳定性的长程影响,研究的基于金刚石的纳米模型包括薄膜、团簇和纳米线。我们理论的计算和分析结果与以前的实验测试和理论模拟都是完全吻合的。在第三章中,我们主要利用第一性原理计算来模拟石墨烯吸附衬底的原子和电子结构性质,并研究石墨烯与衬底的相互作用对其界面处电子性质的影响,研究的石墨烯衬底包括硅(Silicon)、金刚石(Diamond)、钛酸锶(SrTiO3)、氧化锌(ZnO)等表面。在第四章中,我们主要利用第一性原理计算来设计和研究基于硅烯的可能存在的实际应用,包括多孔硅烯作为气体提纯薄膜和二维硅烯-石墨烯杂化纳米复合物用于可调控的p-n节。在论文的附录部分,我们主要介绍本组自主研发的线性标度程序ONPAS。我们的主要工作就是并且对ONAPS进行并行化处理,以实现其对大型纳米材料的电子结构性质的大规模并行计算。测试结果显示,ONAPS并行计算远远优于SIESTA本身的并行计算,包括并行计算时间内存和并行计算效率两个方面。更多还原

【Abstract】 Nanomaterials in a new generation of nanoscale materials, with a variety of exotic features, showing specific optical, electrical, magnetic, thermal, mechanical, mechan-ical and other physical and chemical properties, which makes nanotechnology rapidly penetrated into different kinds of research fields, attracting many physicists, chemists and materials scientists at home and abroad and also becoming the world’s most popu-lar scientific research hot spots. Physicists interested in nanomaterials because it has a unique electromagnetic properties, chemists because of its chemical activity and poten-tial application value, materials scientists interested in its hardness, strength and flexi-bility. There is no doubt that today’s world economic development and social progress of nano-materials-based nanotechnology is bound to have an important impact. There-fore, the scientific research of nanomaterials has a very important significance. Among them, carbon nanomaterials is one of the most popular scientific research material.It is well known that the carbon element is one of the most important elements in nature, having different kinds of orbital hybridization characteristics, including sp, sp2and sp3. Therefore, carbon-based nanomaterials are diverse, including common graphite and diamond, and recently popular carbon nanotubes, carbon nanowires, fullerenes, and graphene. Recently, silicon monolayer similar to graphene, also known as silicene, has also been confirmed theoretically and experimentally, may become the latest pop-ular nanomaterials.In addition, in recent decades, based on the rapid development of computer sci-ence and technology with each passing day makes the theoretical basis of the first-principles calculations based on density functional theory and numerical calculation algorithm has also made a number of significant research progress and application prospects, especially in nano-materials science has made important research results, has attracted wide attention both at home and abroad. In this article, we mainly use the first-principles method to study and calculation of the electronic structure and its possible practical application of new carbon nanomaterials. In the first chapter, we briefly introduce the basic knowledge of the density func-tional theory, including the core issue of the Hartree-Fock equations, the Kohn-Sham equations and density functional theory:the exchange-correlation energy functional. Finally, we also introduced the common package based on density functional theory calculations.In the second chapter, we mainly use the structure and electromagnetic properties of first-principles calculations to study the diamond-based nanomaterials hosting the NV centers. Based on the electric double layer model, we found that the diamond surface decorations and sizes have effects on the relative stability of the NV0and NV-centers. Our considered three different diamond-based nanomaterials, including films, clusters and nanowires.In the third chapter, we mainly use the first-principles calculations to simulate the electronic structure of graphene on substrates. The interaction between graphene and its substrate has been studied, including silicon, diamond, strontium titanate (SrTiO3) and zinc oxide (ZnO).In the fourth chapter, we mainly use the first-principles calculations to design and study practical applications of silicene, including porous silicene as gas purification membrane and two-dimensional hybrid silicene-graphene nanocomposites for tunable p-n junctions.In the appendix, we introduced the linear scale program named ONPAS developed by our group. Our main job is to parallel the ONAPS and achieve high-performance parallel computing efficiency for large-scale electronic structure of nanomaterials. Our test results show that the parallel computing of ONPAS is far superior to SIESTA, including calculation time, memory and parallel efficiency.更多还原