Materials World Network: First-Principles-Based, Large-Scale Modeling of Nanostructural Evolution Binary Alloys

材料世界网络：基于第一原理的纳米结构演化二元合金大规模建模

• 批准号: 0650406
• 负责人: Gus Hart
• 金额: $ 24.9万
• 依托单位: Brigham Young University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0650406&HistoricalAwards=false
• 关键词: Materials; World; Network; First; Principles

This award supports an ongoing international collaboration in materials modeling between researchers in the US and in Germany. The aim of this work is to model and understand the evolution of characteristic nanoclusters, so-called precipitates, in alloys based on first-principles input and large-scale simulations. The research group of S. Mueller in Erlangen, Germany, is noted for its interest in low-dimensional aspects of materials and developing a cluster expansion (CE) methodology for surfaces. The research group of G. Hart has experience in studying vacancy-ordering compounds, extensive CE methodology development, and a successful undergraduate research program. The project builds on the international collaboration between the PIs that started with their previous award, NSF-0244183 and DFG-MU1648/3. Under that project the PIs developed an evolutionary approach (i.e., genetic algorithm) for constructing model Hamiltonians; modeled the difficult one-dimensional and two-dimensional superstructures of the Cu-Pd system with remarkable accuracy; studied vacancy-ordering systems in transition-metal (TM) carbides and nitrides, finding a surprising connection to TM chalcogenides; studied refractory bcc compounds. The complementary strengths of the PIs respective groups create a synergy which has been essential to the success of the project so far. Additionally, the project and its collaboration have supported several graduate students and leveraged G. Hart's strong commitment to undergraduate research, providing opportunities for almost a dozen undergraduate students, including several participants from underrepresented groups. Building on the first two years' work, the PIs will extend their methodology to large-scale modeling of precipitate evolution; modeling precipitate nucleation, growth, and ripening; modeling vacancy ordering. During this project, they will:1. Develop further advanced kinetic and thermodynamic Monte Carlo codes and study precipitation in fcc-, bcc-, and hcp-based metal alloys. This includes an extension to non-Bravais crystals (see point 3.).2. Extend existing genetic algorithm approaches for optimizing alloy configurations (e.g., groundstate searches) to simulation cell-independent models that can explore larger search spaces. 3. Develop new codes built on an extended cluster expansion formalism and study non-Bravais crystal systems (e.g., hexagonal-close-packed systems), including an explicit treatmentof long-range strain effects for the first time in these systems. The broader impacts of the project include:1. For the first time, a large range of important alloy types can be explored, not just cubic systems. The ability to treat hcp systems opens the door to Mg-based and Ti-based intermetallic systems and the large class of wurtzite-based III-V and II-IV semiconductor materials.2. These extended methods and codes will be freely available to other researchers, including thegenetic algorithms for model Hamiltonian construction and searching crystal structures. 3. Continue to provide undergraduate students, especially those from underrepresented groups,with research experience and one-to-one faculty mentoring. The US side of the collaborationhas very successfully integrated undergraduate research experiences into the project and the collaboration. Students are involved long-term, from project inception to final publication.This award is co-funded by the Europe program of the NSF Office of International Science and Engineering.

该奖项支持美国和德国研究人员之间正在进行的材料建模国际合作。 这项工作的目的是模拟和理解的演变的特征纳米团簇，所谓的沉淀物，在合金的第一性原理输入和大规模模拟的基础上。S.德国埃尔兰根的Mueller以其对材料低维方面的兴趣和开发表面的簇扩展（CE）方法而闻名。G.哈特在研究空位有序化合物、广泛的CE方法开发以及成功的本科研究项目方面具有丰富的经验。该项目建立在PI之间的国际合作基础上，该合作始于他们之前的奖项NSF-0244183和DFG-MU 1648/3。在该项目下，PI开发了一种渐进的方法（即，他使用遗传算法（Genetic Algorithm）来构建模型哈密顿量;以惊人的精度模拟了Cu-Pd系统的一维和二维超结构;研究了过渡金属（TM）碳化物和氮化物中的空位有序系统，发现了与TM硫属化物的惊人联系;研究了难熔bcc化合物。项目负责人各小组的优势互补，产生了协同作用，这对项目迄今的成功至关重要。 此外，该项目及其合作支持了几个研究生和杠杆G。哈特对本科研究的坚定承诺，为近12名本科生提供了机会，其中包括来自代表性不足群体的几名参与者。在前两年工作的基础上，PI将把他们的方法扩展到沉淀演变的大规模建模;模拟沉淀成核、生长和成熟;模拟空位有序。在这个项目中，他们将：1。进一步开发先进的动力学和热力学蒙特卡罗程序，研究面心立方、体心立方和六方晶系金属合金中的沉淀。这包括对非布拉维晶体的扩展（见第3点）。2.扩展现有的遗传算法方法来优化合金配置（例如，基态搜索）来模拟可以探索更大搜索空间的与单元无关的模型。3.开发基于扩展的簇扩展形式主义的新代码，并研究非布拉维晶体系统（例如，hexagonal-close-packed systems），包括在这些系统中首次明确处理长程应变效应。该项目更广泛的影响包括：1。这是第一次，可以探索大范围的重要合金类型，而不仅仅是立方系统。处理hcp系统的能力为Mg基和Ti基金属间化合物系统以及大类纤锌矿基III-V和II-IV半导体材料打开了大门。这些扩展的方法和代码将免费提供给其他研究人员，包括用于模型哈密顿构造和搜索晶体结构的遗传算法。3.继续为本科生，特别是那些来自代表性不足的群体，提供研究经验和一对一的教师指导。美国方面的合作非常成功地将本科生的研究经验融入到项目和合作中。从项目开始到最终出版，学生们都长期参与其中。该奖项由美国国家科学基金会国际科学与工程办公室的欧洲项目共同资助。