CAREER: Energy Landscape Based Tools for Modeling Materials at the Nanoscale

职业：基于能源景观的纳米尺度材料建模工具

• 批准号: 0448721
• 负责人: Thomas Truskett
• 金额: $ 40万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-03-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0448721&HistoricalAwards=false
• 关键词: CAREER; Energy; Landscape; Based; Tools

(CAREER) Energy Landscape Based Tools for Modeling Materials at the NanoscaleProject SummaryMaterials confined to small dimensions often behave differently than in the bulk. In particular,they exhibit thermodynamic, kinetic, and mechanical limits of stability that depend on sample size,shape, and the physical characteristics of their interfaces. Property modifications that featureprominently in 'nanoconfined' systems include the appearance of surface-induced phase transitions,shifts of the bulk glass transition temperature, and the emergence of interface-mediated modes ofmechanical failure. The technological relevance of these issues for solid materials has long beenappreciated in industrial settings because many applications require micro- or nanoscale componentsthat can exhibit mechanical integrity over a broad range of conditions. Unfortunately, acomprehensive theoretical approach for predicting these effects has been slow to develop.Intellectual Merit. The PI propose to introduce a new theoretical framework based on exploring theeffects of confinement on a material's potential energy landscape. Although energy landscapes havebeen primarily used to study biomolecules, small molecular clusters, and bulk materials, they argue that they are particularly well suited to provide insights into the implications of nanoscale confinement for materials. Specifically, the hypothesis is that the stability of glassy nanostructures (relative to the bulk) can be understood in terms of how confinement changes their energy landscapes. To test this idea, the PI's have performed several "proof of concept" studies for our new landscape basedformalism.Based on the success of these studies, the PI'spropose to fully develop and apply this approach in atwo-pronged research program that will allow us to address systems of experimental relevance. Thefirst part calls for using landscape based simulation methods to probe the molecular-levelprocesses that control deformation, yielding, and failure in bulk and nanoconfined metallicglasses. This study will help to elucidate how interfaces and confinement impact the novel mechanicaland structural responses of metallic glasses to various types of loading. The models are propose toinvestigate and provide guidance into the potential mechanical behavior of metallic glasses innanocomposite materials. The second proposed effort is the development of a new approach thatcombines the energy landscape framework with classical density functional theory (DFT) forinhomogeneous fluids. The resulting landscape based DFT will provide new predictions for thebehavior of both liquid and glassy states in nanoconfined environments. The proposed work willprovide a sound foundation for collaborations to study dynamic fracturing of nanoscale glasses viaexperiments and large-scale simulations. The PI's also propose an associated education plan that willengage the public in a dialogue about the modern roles of computing and nanoscience in engineering.It does so by introducing new undergraduate and graduate level courses and a new type ofeductational tool called a theory-driven learning module. This module can be readily created withmethods that are routinely used in the PI's research group, illustrating a practical benefit of integratingteaching and research. Finally, a novel outreach program is outlined that will bring leaders of Austin'stechnology sector into the K-12 classrooms of smaller Texas towns.Broader Impacts. The research methods introduced here could lead to significant improvementsin the understanding of material stability at the nanoscale. This understanding is urgently neededbecause the current lack of knowledge presents a formidable barrier to conceiving new nanoscaleprocesses and designing nanostructured materials for use in advanced material, biomedical, andsemiconductor applications. These applications, ranging from stronger composite materials to smallerand faster computers, would substantially impact the economy and the everyday lives of millions. Theresearch is integrated with broader initiatives that seek not only to enhance the educational experienceof students at all levels, but also to inform the public about science, engineering, and the careeropportunities in both. The plan recognizes that engineers are increasingly involved in developingprocesses that must perform robustly on small length scales, and it introduces both courses andeducational tools that will prepare them for this challenge. The novel K-12 outreach program that isproposed will serve as a means for engaging the public in a meaningful dialogue about the societalimpact of science and the possibilities of engineering and science "as a career".

（CAREER）基于能源景观的纳米尺度材料建模工具项目摘要材料局限于小尺寸通常表现得不同于散装。特别是，它们表现出热力学，动力学和机械稳定性的限制，这取决于样品的大小，形状和它们的界面的物理特性。在“nanobolined”系统中，性能修饰的显著特征包括表面诱导相变的出现、本体玻璃化转变温度的变化以及界面介导的机械失效模式的出现。固体材料的这些问题的技术相关性一直在工业环境中得到重视，因为许多应用需要在广泛的条件下表现出机械完整性的微米或纳米级组件。不幸的是，用于预测这些效应的复杂理论方法发展缓慢。PI建议引入一个新的理论框架，该框架基于探索约束对材料势能景观的影响。虽然能量景观主要用于研究生物分子，小分子团簇和散装材料，但他们认为，它们特别适合于提供对材料纳米级限制影响的见解。具体而言，该假设是玻璃状纳米结构的稳定性（相对于本体）可以根据限制如何改变其能量景观来理解。为了测试这个想法，PI已经为我们新的基于景观的形式主义进行了几次“概念验证”研究。基于这些研究的成功，PI建议在双管齐下的研究计划中充分开发和应用这种方法，这将使我们能够解决实验相关的系统。第一部分要求使用景观为基础的模拟方法来探测控制变形，屈服，并在散装和nano-confined metallicglasses故障的分子水平的过程。这项研究将有助于阐明界面和约束如何影响金属玻璃对各种类型载荷的新型力学和结构响应。这些模型为研究纳米复合材料中金属玻璃的潜在力学行为提供了指导。第二个建议的努力是发展一种新的方法，结合能量景观框架与经典的密度泛函理论（DFT）的非均匀流体。由此产生的景观为基础的DFT将提供新的预测的行为的液体和玻璃态在纳米密闭环境。这项工作将为通过实验和大规模模拟研究纳米玻璃的动态断裂提供良好的合作基础。PI还提出了一个相关的教育计划，让公众参与到关于计算和纳米科学在工程中的现代作用的对话中来。它通过引入新的本科生和研究生课程以及一种称为理论驱动学习模块的新型教育工具来实现。这个模块可以很容易地创建与PI的研究小组中经常使用的方法，说明了整合教学和研究的实际好处。最后，一个新的外展计划概述，将使奥斯汀的技术部门的领导人到K-12教室较小的得克萨斯州城镇。这里介绍的研究方法可能会导致在纳米材料稳定性的理解显着改善。这种理解是迫切需要的，因为目前知识的缺乏对构思新的纳米尺度工艺和设计用于先进材料、生物医学和半导体应用的纳米结构材料构成了巨大的障碍。这些应用，从更强的复合材料到更小更快的计算机，将对经济和数百万人的日常生活产生重大影响。该研究与更广泛的举措相结合，这些举措不仅旨在提高各级学生的教育经验，而且还向公众宣传科学，工程和两者的职业机会。该计划认识到，工程师越来越多地参与开发必须在小长度尺度上稳健运行的过程，并引入了课程和教育工具，使他们为这一挑战做好准备。新的K-12外展计划将作为一种手段，让公众参与有意义的对话，讨论科学的社会影响以及工程和科学“作为职业”的可能性。