Computational Methods for Problems in Material Science

材料科学问题的计算方法

• 批准号: 0207402
• 负责人: Peter Smereka
• 金额: $ 20.87万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2005-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0207402&HistoricalAwards=false
• 关键词: Computational; Methods; Problems; Material; Science; Computational; Methods; Problems; Material; Science

This project concerns the development of efficient numericalmethods for problems related to material science. Theinvestigator studies computational issues concerning thenumerical solution of continuum models for thin film growth. Manyof these models include effects for surface diffusion, which is anonlinear 4th order term. Consequently, these models are verystiff from a computational point of view. Because the surfacediffusion term is nonlinear, it is difficult to use implicitmethods. The investigator introduces a new semi-implicit levelset method for solving motion by surface diffusion. He uses thisnew method to incorporate the effects of surface diffusion intomodels of polycrystalline thin films. He also develops a newapproach for computing island dynamics, where the adatoms on theterraces are considered as a continuum field and the atoms on theedge of the island are treated discretely. This approach retainsthe potential advantage of continuum methods but at the same timepreserves the discrete and stochastic effects present in islanddynamics. The investigator includes effects of edge diffusion,surface tension, nucleation, and elasticity. An importantcomputational aspect of this problem is the numerical solution ofthe diffusion equation in a complex domain. The investigatorexamines new methods for the efficient solution of this problem. Thin films occur in a large number of applications, fromcoatings on bearings to semi-conductor devices. In many casesthese films are not single crystals but instead arepolycrystalline and the quality of the film can depend on itstexture. Films with good biaxial texture are close to being asingle crystal and have applications in the manufacture ofsuper-conducting tapes, for example. One important physicaleffect in determining the evolution of the texture is surfacediffusion, but this is difficult to implement numerically and theinvestigator plans to develop a semi-implicit level set method tostudy the growth of polycrystalline thin films. The work herecould help improve the fundamental understanding of these films.Another important process by which thin films are made ismolecular beam epitaxy. The standard method for accuratesimulation of this process is kinetic Monte Carlo. In manysituations this method can be slow, and continuum models have thepotential to greatly increase the speed of such computations.However, continuum models ignore discrete and stochastic effects.The investigator develops hybrid models that have good physicalfidelity but offer considerable computational speed.

该项目涉及针对与材料科学有关的问题的有效数值方法的发展。 评估器研究有关薄膜生长的连续模型的当时解决方案的计算问题。 这些模型的许多模型都包含表面扩散的效果，即鼻线第四阶项。 因此，从计算的角度来看，这些模型是非常稳定的。 由于表面浮术语是非线性的，因此很难使用隐式方法。 研究者介绍了一种新的半图层水平集方法，用于通过表面扩散来解决运动。 他使用This New方法结合了多晶薄膜的表面扩散intomodels的影响。 他还开发了一种用于计算岛动力学的新方法，在该动力学中，thetraces上的Adatoms被认为是连续性领域，并且该岛上的原子被离散地对待。 这种方法保留了连续方法的潜在优势，但同时提出了Islanddemangics中存在的离散和随机效应。 研究者包括边缘扩散，表面张力，成核和弹性的影响。 该问题的重要计算方面是复杂域中扩散方程的数值解。 调查方法有效解决此问题的新方法。 薄膜发生在大量应用中，从轴承上的涂料到半导体设备。 在许多Casesthese中，电影不是单一晶体，而是蛋白酶结晶，胶片的质量可能取决于ItStexture。 具有良好双轴纹理的膜接近是敏感的晶体，例如，在制造磁带的制造中应用。 确定纹理演变的一种重要物理效果是表面浮液，但这很难以数值实施，而感染者计划开发半层次级别设置方法tostostudy tostody tostody totostudy是多晶薄膜的生长。 该作品还可以帮助提高对这些电影的基本理解。另一个重要过程，使薄膜成为伊斯莫利束外延。 精确模拟此过程的标准方法是动力学蒙特卡洛。 在Manysitusation中，此方法可能会很慢，并且连续模型具有大大提高此类计算速度的潜在。