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首页> 外文期刊>Computer Methods in Applied Mechanics and Engineering >Concurrent Quantum/continuum Coupling Analysis Of Nanostructures
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Concurrent Quantum/continuum Coupling Analysis Of Nanostructures

机译：纳米结构的同时量子/连续谱耦合分析

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A general multiscale computational framework that concurrently couples the quantum-mechanical model with the continuum model is developed. This approach is then used to study the electronic properties of single-walled carbon nanotubes (CNTs) influenced by geometry and deformation. The electronic properties of the CNT, such as the band structure and band gap, are intimately connected to its electrical and thermal properties, mechanical stiffness, failure strength, chemical reactivities and many others. The CNT geometry is featured by a cylindrical-shaped structure, which leads to a mixture of the electronic structures that were originally present in graphite. These important effects are incorporated in a coarse-grained tight-binding model based on an extension to the Bloch theorem and the virtual atom cluster model developed previously by the authors. With this approach, we study the correlation among the electronic structures/properties, CNT geometry and applied deformation for a wide variety of tubes. The major technical ingredients and findings are (1) Compared with the computational cost of O(n_e~3) of the full-scale tight-binding calculation with n_e being the electronic base functions used, we have developed an efficient concurrent approach as it scales with O(N_G) with N_G being the number of quadrature points; (2) We have established a new coarse-grained cluster model that provides a direct way of coupling deformation mapping with the quantum-mechanical model. A unique feature of this coarse-grained model is that it does not use any stress and strain concepts as in a standard continuum approach; (3) We report strong influences of CNT geometry on its electronic properties. For zigzag tubes with chiral index of (n,0) and radius r, the band gap E_g α r~(-0.695) when the remainder of n divided by 3 (mod(n,3)) is 1 and E_g α r~(-1.109) when mod(n,3) = 2; (4) We report significant changes in the band gap and electrical conductance as functions of the applied tensile strain and twist. Transitions from metal to semiconductor and vice versa are observed; (5) There is a weak coupling between the band gap, electrical conductance and applied bending angle. Based on extensive studies, we conclude that the electron-mechanical coupling relations obtained in this work are more robust than the previous analytical studies in that it takes into account the important effects of curvature and relaxation. The simulation results highlight the importance of the concurrent coupling among the electronic properties, CNT geometry and mechanical deformation.
机译：建立了将量子力学模型与连续模型同时耦合的通用多尺度计算框架。然后，该方法用于研究受几何形状和变形影响的单壁碳纳米管（CNT）的电子性能。碳纳米管的电子性能，如能带结构和能带隙，与其电学和热学性能，机械刚度，破坏强度，化学反应性以及许多其他方面息息相关。 CNT的几何特征是圆柱形结构，这导致了最初存在于石墨中的电子结构的混合。基于对Bloch定理和作者先前开发的虚拟原子簇模型的扩展，将这些重要的影响并入了粗粒度紧密绑定模型中。通过这种方法，我们研究了各种管的电子结构/性能，CNT几何形状和应用变形之间的相关性。主要技术成分和发现是：（1）与以n_e为电子基础函数的全尺寸紧约束计算的O（n_e〜3）的计算成本相比，我们开发了一种有效的并发方法O（N_G），N_G为正交点数； （2）我们建立了一个新的粗粒度簇模型，该模型提供了将变形映射与量子力学模型耦合的直接方法。该粗粒度模型的独特之处在于它不像标准连续方法那样使用任何应力和应变概念。 （3）我们报道了碳纳米管几何形状对其电子性能的强烈影响。对于手征指数为（n，0）和半径r的曲折管，当n的余数除以3（mod（n，3））为1且E_gαr〜时，带隙E_gαr〜（-0.695） （-1.109）当mod（n，3）= 2时; （4）我们报告了带隙和电导率随着所施加的拉伸应变和扭曲而显着变化。观察到从金属到半导体的转变，反之亦然。 （5）带隙，电导率和施加的弯曲角度之间存在弱耦合。基于广泛的研究，我们得出的结论是，这项工作中获得的电子-机械耦合关系比以前的分析研究更牢固，因为它考虑了曲率和松弛的重要影响。仿真结果突出了电子性能，CNT几何形状和机械变形之间同时耦合的重要性。

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