Discovery and Design with the FAST Principle: Following Local Models of Stability to Emergent Phenomena in Intermetallic Structures

非技术性总结： 金属材料在促进繁荣和国家安全方面所发挥的作用正在不断发展。 这些材料的研究已经越来越多地从机械性能，导电性和耐腐蚀性转向与电子量子性质相关的更奇特的效应，例如电流的无电阻传导，先进的磁现象以及热能转化为电能。 这些特性的基础是材料原子在微观水平上形成的几何排列的惊人多样性。 理解和学习如何控制这些排列是设计新金属材料的一个限制因素。 该项目通过建立一个预测模型来促进科学的进步，该模型可以预测金属中相邻原子之间不同类型的相互作用如何传播，以形成观察到的复杂原子排列，为发现新材料开辟道路。 理论计算被用于分析这些相互作用并探索其含义，同时扫描结构信息数据库以识别金属材料，其中预期在原子水平上的有趣行为。 理论预测指导新金属化合物的实验研究，为正在开发的模型提供反馈。 该项目还影响了STEM领域的培训和教育，重点是固态化学。 新的内容正在为科学通过漫画网站，它使用相关的类比和幽默，以激发对科学的兴趣。 此外，正在与LibreTexts合作编写免费在线教科书《互动固态化学》，以便向广大学生和教育工作者分发。 在这里，介绍材料的漫画与互动工具相结合，以促进学生的积极参与，例如可以在三维空间中操作的结构模型。 研究小组还通过外联活动和辅导，增加了代表性不足群体成员对科学的参与。技术概要：金属间化合物相是潜在功能材料的丰富来源，因为它们联合收割机无与伦比的结构多样性和有价值的物理性能。 然而，为了充分实现这一承诺，仍然需要设计原则来指导这些相的晶体结构，以便系统地研究它们的结构-性能关系，并可以制备具有针对特定应用的结构的材料。 在这个项目中，需要这样的设计原则正在解决通过发展的预测能力的挫折和允许的结构转变（FAST）的方法。 在一个结构可能经历的许多转变或修改中，那些涉及影响稳定性的各种因素之间的合作的转变或修改可以预期在能量上胜过那些因素相互冲突的转变或修改。 在这项工作的一个组成部分，FAST方法的范围正在扩大，通过计算机辅助筛选晶体结构数据库的几何特征与容易的过渡，产生候选结构的理论分析和实验研究。 同时，FAST图片的完整性进行了测试和改进，通过其应用程序的结构偏好，涉及18-n+m异构体在过渡金属-主族金属间化合物，其中各种键合配置使用不同的化合物，以坚持18-n电子计数规则，为任何给定的电子计数。 最后，预测的FAST计划的影响进行了探索，通过将这些图片转化为力场模型的大规模分子动力学模拟。 涌现的结构特性，如不相称的调制或相变的预测，追求实验。 在所有这些努力中，实验结果被用来完善理论和概念方法。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估的支持。

NON-TECHNICAL SUMMARY: The role played by metallic materials in the advancement of prosperity and national security is evolving. Research in these materials has increasingly shifted from mechanical properties, conductivity, and corrosion resistance to more exotic effects related to the quantum nature of electrons, such as the resistance-free conduction of electric currents, advanced magnetic phenomena, and the conversion of thermal energy into electric energy. Underlying these properties is a startling diversity in the geometrical arrangements that the atoms of materials can form at the microscopic level. Understanding and learning how to control these arrangements is a limiting factor in the design of new metallic materials. This project is promoting the progress of science by building a predictive model for how different types of interactions between neighboring atoms in a metal propagate to form the observed complex atomic arrangements, opening avenues to the discovery of new materials. Theoretical calculations are being used to analyze these interactions and explore their implications, while databases of structural information are scanned to identify metallic materials in which intriguing behavior at the atomic level are expected. The predictions of theory are guiding experimental investigations of new metallic compounds, which provide feedback on the models being developed. This project also impacts the training and education in the STEM fields, with an emphasis on solid state chemistry. New content is being created for the Science through Comics website, which uses relatable analogies and humor to inspire interest in science. In addition, the free on-line textbook Interactive Solid State Chemistry is being developed for dissemination to a broad range of students and educators in collaboration with LibreTexts. Here, comics introducing the materials are integrated with interactive tools for active student engagement, such as structure models that can be manipulated in three dimensions. The research team is also increasing the participation of members of underrepresented groups in the sciences through outreach activities and mentoring. TECHNICAL SUMMARY: Intermetallic phases are a rich source of potential functional materials, as they combine an unparalleled structural diversity with valuable physical properties. To fully realize this promise, however, design principles are still needed for guiding the crystal structures of these phases, such that their structure-properties relationships can by systematically investigated, and materials with structures tailored to specific applications can be prepared. In this project, the need for such design principles is being addressed through the development of the predictive capabilities of the Frustrated and Allowed Structural Transitions (FAST) approach. Of the many transformations or modifications a structure could potentially undergo, those that involve cooperation between the various factors influencing stability can be expected to out-compete energetically those in which the factors conflict with each other. In one component of this work, the scope of the FAST approach is being expanded through the computer-aided screening of crystal structure databases for geometrical features associated with easy transitions, yielding candidate structures for theoretical analysis and experimental investigation. Simultaneously, the completeness of the FAST picture is tested and improved through its application to the structural preferences involving 18-n+m isomerism in transition metal-main group intermetallics, in which a variety of bonding configurations are used by different compounds to adhere to the 18-n electron counting rule for any given electron count. Finally, the predictive implications of the FAST schemes are explored by translating these pictures into force field models for large-scale molecular dynamics simulations. Predictions of emergent structural properties, such as incommensurate modulations or phase transitions, are pursued experimentally. In all of these endeavors, the experimental results are being used to refine the theoretical and conceptual approach.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.