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

非技术概述：金属材料在促进繁荣和国家安全方面所发挥的作用正在演变。对这些材料的研究越来越多地从机械性能、电导率和耐腐蚀性转向与电子量子性质有关的更奇特的效应，如电流的无电阻传导、先进的磁现象和热能转化为电能。在这些特性的背后，是材料原子在微观层面上可以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预测金属中相邻原子之间不同类型的相互作用如何传播，从而形成观察到的复杂原子排列，从而促进科学的进步，为发现新材料开辟了道路。理论计算被用来分析这些相互作用并探索它们的含义，而结构信息数据库被扫描以识别金属材料，其中在原子水平上的有趣行为是预期的。理论预测指导着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。新内容正在为“科学漫画”网站创建，该网站使用相关的类比和幽默来激发人们对科学的兴趣。此外，与LibreTexts合作开发的免费在线教科书“互动固态化学”正在向广大学生和教育工作者传播。在这里，介绍材料的漫画与学生积极参与的互动工具相结合，例如可以在三维空间中操作的结构模型。该研究小组还通过外联活动和指导增加了代表性不足群体成员在科学领域的参与。技术概述：金属间相是潜在功能材料的丰富来源，因为它们结合了无与伦比的结构多样性和宝贵的物理性质。然而，为了充分实现这一前景，仍然需要设计原则来指导这些相的晶体结构，从而可以系统地研究它们的结构-性能关系，并可以制备适合特定应用的结构材料。在这个项目中，对这种设计原则的需求正在通过开发挫败和允许结构转换（FAST）方法的预测能力来解决。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，可以预期会大大超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中，FAST方法的范围正在通过计算机辅助筛选晶体结构数据库来扩展，以寻找与容易转变相关的几何特征，从而产生用于理论分析和实验研究的候选结构。同时，通过对过渡金属-主基团金属间化合物中18-n+m异构体的结构偏好进行测试和改进，FAST图的完整性得到了验证。在过渡金属-主基团金属间化合物中，对于任意给定的电子计数，不同的化合物使用不同的键构型来遵守18-n电子计数规则。最后，通过将这些图像转化为大规模分子动力学模拟的力场模型，探讨了FAST方案的预测意义。对突发性结构特性的预测，如不适应调制或相变，是通过实验进行的。在所有这些努力中，实验结果被用来完善理论和概念方法。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

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.