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首页> 外文期刊>Computer physics communications >Multiresolution algorithms for massively parallel molecular dynamics simulations of nanostructured materials
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Multiresolution algorithms for massively parallel molecular dynamics simulations of nanostructured materials

机译：用于纳米结构材料的大规模并行分子动力学模拟的多分辨率算法

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Multimillion atom molecular-dynamics (MD) simulations are performed to investigate dynamics of oxidation of aluminum nanoclusters and properties and processes in nanostructured silicon carbide (n-SiC) and nanostructured amorphous silica (n-a-SiO_2). The simulations are based on reliable interatomic interactions that include both ionic and covalent effects. The simulations are carried out on parallel architectures using highly efficient O(N) multiresolutions algorithms which include an adaptive load-balancing approach based on wavelets and a data-compression scheme based on fractals. Results from the oxidation simulation reveal a passivating amorphous oxide layer of thickness ～40 A, which is in excellent agreement with experiments. The oxide layer is amorphous and has mixed tetrahedral, Al(O_(1/4))_4, and octahedral, Al(O_(1/6))_6, configurations. The average mass density in the oxide region is 75% of the bulk alumina density. local stresses in the oxide scale are analyzed and their correlation with the dynamics of oxidation is determined. Sintering, structural correlations, and mechanical behavior of n-SiC and n-a-SiO_2 are investigated. In the case of n-SiC, both experiment and simulation indicate the onset of sintering around 1500 K which is much lower than the sintering temperature for coarse-grained SiC. In both n-SiC and n-a-SiO_2, pores are found to be self-similar. They have a fractal dimension close to 2 and their surface roughness exponents are ～0.5. Pair-distribution functions and bond-angle distributions reveal a crystalline core and an amorphous interface in the consolidated n-SiC, In the case of nanophase silica glasses, the short-ranger order (SRO) is similar to that in the bulk glass but not the intermediate-range order (IRO). In the nanophase system the first sharp diffraction peak (FSDP), the signature of IRO, has a much smaller height and is shifted toward smaller k relative to the FSDP in the bulk system. The elastic moduli of nanophase silica glasses scale with the density as ～ρ~(3.5); the bulk, shear and Young's moduli of n-SiC scale as ～ρ~η, where η is 3.51 ± 0.02, 3.29 ± 0.06, and 3.34 ± 0.03, respectively.
机译：进行了数百万个原子分子动力学（MD）模拟，以研究铝纳米团簇的氧化动力学以及纳米结构的碳化硅（n-SiC）和纳米结构的无定形二氧化硅（n-a-SiO_2）的性质和过程。该模拟基于可靠的原子间相互作用，其中包括离子效应和共价效应。使用高效的O（N）多分辨率算法在并行体系结构上进行仿真，该算法包括基于小波的自适应负载平衡方法和基于分形的数据压缩方案。氧化模拟的结果表明，钝化的非晶氧化物层厚度约为40 A，与实验非常吻合。氧化物层是非晶的，并且具有混合的四面体Al（O_（1/4））_ 4和八面体Al（O_（1/6））_ 6的构型。氧化物区域的平均质量密度为氧化铝总密度的75％。分析了氧化皮中的局部应力，并确定了它们与氧化动力学的关系。研究了n-SiC和n-a-SiO_2的烧结，结构相关性和力学行为。在n-SiC的情况下，实验和仿真均表明烧结开始于1500 K左右，这远低于粗晶SiC的烧结温度。在n-SiC和n-a-SiO_2中，都发现孔是自相似的。它们的分形维数接近2，表面粗糙度指数为〜0.5。配对分布函数和键角分布揭示了固结n-SiC中的晶核和非晶界面。在纳米相石英玻璃的情况下，短程有序（SRO）与块状玻璃中的短程有序（SRO）相似中间范围订单（IRO）。在纳米相系统中，第一个尖峰衍射峰（FSDP）是IRO的特征，其高度小得多，并且相对于本体系统中的FSDP向着较小的k偏移。纳米相石英玻璃的弹性模量为〜ρ〜（3.5）。 n-SiC鳞片的体积模量，剪切模量和杨氏模量为〜ρ〜η，其中η分别为3.51±0.02、3.29±0.06和3.34±0.03。

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