【作者】 谭凯；

【导师】 王南钦； 林梦海；

【作者基本信息】 厦门大学 ， 物理化学， 2002， 博士

【摘要】 纳米材料设计与研究的计算与模拟随着纳米技术的发展而日益受到重视，在模拟研究中，原子间相互作用势是一个根本性的关键问题，如何精确地描述它是模拟取得较好结果的关键所在。目前还没有统一的方法和模型去解决纳米材料中的问题，进入到纳米尺度层次后，经验势模拟方法已跟不上材料研究的发展。本文试图用从头算数据导出的合适的原子相互作用势，应用于纳米材料的模拟中，研究工作主要包括三个方面： 1．纳米金属团簇的计算模拟 利用密度泛函方法对小Cu簇(n=2～13)进行计算并构造了铜原子簇原子间相互作用多体势，用全局优化模拟了中等和大的铜团簇的结构与稳定性，结果证实了铜团簇具有五次对称性和幻数现象。对T1簇的计算和模拟得到与铜簇并不一致的的结果，具有六次轴对称的结构，这反映出电子结构的不同是影响它们结构的主要因素。原子间相互作用不具有随意外推的应用，但针对不同金属的原子间相互作用的模拟结果是和实验相一致的。 2．纳米合金体系的计算模拟 通过用DFT详细地对NiTi二元合金簇的研究导出其原子间相互作用并加以模拟研究纳米晶界结构与稳定性，结果表明DFT导出的相互作用函数更适合研究纳米材料晶界或非晶纳米合金行为，而用经验势能函数的模拟纳米合金相变有很好的模拟结果。这反映出原子间相互作用的不足，需要加以修正以满足普适的要求。DFT结合实验数据导出的嵌入原子势用于纳米NIZr合金热力学性质的分子动力学模拟，模拟结果证实了纳米合金材料由于界面结构原子分布比较混乱，与常规合金相比体系嫡较大，熔点降低，得到与实验一致的结果。并进一步从逆蒙特卡罗模拟研究了它的微观状态，包括配位情况、键角分布等一系列有用的信息。3.纳米二氧化钦负载金属体系的计算模拟研究 我们对纳米金红石型TIO:吸附K、Cu金属原子进行了DFT研究，并模拟了金属在纳米金红石型TIO:表面的吸附行为，解释了纳米金属簇在金红石型TIO:表面吸附的行为，预测了纳米金属团簇在表面生长的机理。同时也证实了嵌入簇模型和裸簇模型能够用于计算纳米二氧化钦负载金属体系的能量和电子性质。 在本文的最后一章，我们详细地探讨了适用于纳米材料的嵌入原子模型的理论基础、数学表示和改进形式，建立了与其它模型方法和函数间的关联，并通过铜纳米线结构的模拟研究证实了它的有效性，这也揭示着传统的化学观念仍然对新出现的化学问题有着指导意义。更多还原

【Abstract】 From the development of the potentials and possibilities that Nano Sci-Technology presents, it is clear that the computation and simulation of nanoscale materials will continue to become increasingly important. To study of simulations, it is necessary to use the description of the interaction between atoms. The accuracy of the potential used dictates the quality of the simulation results. For nanoscale materials system, There haven’t a uniform model or method to study the details of the nanoscale material designed and function. There have been quite a bit of development to utilize the empirical interatomic potential, but the applicability is inherently limited to easy causing a transferability problem. In the paper, we develop a appropriate interatomic potential via density functional theory(DFT) , simulate well in nanoscalematerial system. There are three sections in this paper.1. Computational simulation in nano size metal clusterIn chapter 2, We use DFT to calculate equilibrium geometries and electronicproperties of Cun(n=2-13) clusters and construct potential function with parameters fitted to potential energy surfaces, use a global minima "basin-hopping" algorithm to obtain minimum-energy structures of Cu clusters for n=13~410. The results show in good agreement with experiments and other calculations. There haven’t a same result for the simulation of Thallium cluster, owing to different electronic structure. This shows that the potential energy function limit to use in certain condition.2. Computational simulation in nano size alloy systemChapters, We applied an approach to the development of many-body interatomic potentials for NiTi, NiZr alloys, The database used for the development of a potential includes both experimental data and a large set of energies of different structures of the material generated by DFT calculations. The molecular dynamic simulation results prove the structure change in nano materials grain size. The thermodynamic and mechanical properties are calculated, it shows the melting point reduce in NiZr alloy nano material. Further we study the microstructure of them by the Reverse Monte Carlo simulation, obtain the a series of information about bond angle - coordinateand so on.3. Metal supported On Ti02(110): Calculation and SimulationChapter 4, The properties of K, Cu supported on the TiO2(110) surfacehave been studied by means of density functional theory, Bare clusters models and embedded cluster model to using to obtain DFT data and construct interatomic potential. The simulation results can explain some phenomena in STM image.In chapter 5, we study in detail the theoretical background , function express and improvement, try to find a relation with other model and method. For a new embedded atom potential, we apply it to simulate copper nanowire structure and energy.更多还原