FRG: Predictive Computational Modeling of Two-Dimensional Materials Beyond Graphene: Defects and Morphologies

非技术总结材料研究部和数学科学部为该奖项提供资金。它支持计算材料科学中的跨学科研究和教育活动，重点是二维(2D)半导体材料的生长。虽然石墨烯是最著名的2D材料，但由于其高导电性，它在器件应用上受到了限制。最近的研究集中在2D半导体材料上，这种材料可以被操纵来阻止或允许电流流动。这些研究活动主要是基于实验探索，因为在决定它们的结构和性质的基本理解上存在差距。该项目旨在通过开发基于相场晶体建模方法的这些系统的生长模型来帮助填补这一空白。这种方法使研究人员能够研究涉及原子大小的微小结构的材料。研究小组将开发、参数化并验证2D半导体材料的相场晶体模型，该模型可用于改进2D材料及其组装的合成过程。模拟还将被用来检查这些材料的结构和原子水平上的相关缺陷。教育活动包括为高中生开设的晶体生长课程，作为加州大学欧文分校加州州立数学和科学暑期学校的一部分，参与科学奥林匹克竞赛，以及其他STEM活动。这些活动将有助于培养未来一代数学家、科学家和工程师。研究生将接受跨学科培训，并将在会议上展示他们的发现，这将增强他们的教育经验。该团队还将作为研究界的资源，分发开发的代码，并在全国会议上组织相场晶体模型研讨会。技术总结材料研究部和数学科学部为该奖项提供资金。它支持计算材料科学中的跨学科研究和教育活动，重点是二维(2D)半导体材料的生长。MoS_2和MoSe_2等二维半导体材料的最近发现加强了对这些材料的研究。由于2D限制，这些材料显示出独特的性质，但与石墨烯不同的是，它们还具有在导电和绝缘状态之间切换的能力，为产生革命性的新技术提供了潜力。这些研究工作主要基于基于各种合成路线的实验探索，对于是什么决定了它们的体相和缺陷结构和形貌，以及它们如何影响它们的性能，在基本的理解上存在着重大的差距。由于所涉及的长度范围很小，计算建模对于发展这种理解是必不可少的。相场晶体(PFC)模型是唯一适合于这一问题的模型，因为它能够解析原子级结构，并且其扩展的时间尺度可与合成相关的时间尺度相媲美。这个多学科项目通过利用PFC模型的最新发展来解决理解与纳米结构形成相关的多尺度现象的挑战，PFC模型跟踪单个原子在扩散时间尺度上的动力学。PFC方法源于经典的密度泛函理论，它自然地考虑了弹性和塑性变形以及晶体缺陷。材料科学家团队和一名数学家将开发一种基于PFC的新计算方法，用于对二维、多组分材料的结构和合成进行建模。模型将通过原子模拟和实验结果进行参数化和验证。将检查在器件应用中必须控制的缺陷，如晶界。计算工具将建立在以前资助下开发的高效数值算法的基础上，并根据新的模型进行调整，并将通过GitHub等储存库进行传播。这些工具将提供一个框架，用于计算发现2D材料合成的基本机制、它们的组装以及它们的原子级结构。教育活动包括为高中生开设的晶体生长课程，作为加州大学欧文分校加州州立数学和科学暑期学校的一部分，参与科学奥林匹克竞赛，以及其他STEM活动。这些活动将有助于培养未来一代数学家、科学家和工程师。研究生将接受跨学科培训，并将在会议上展示他们的发现，这将增强他们的教育经验。该小组还将作为研究界的资源，在国家会议上组织关于相场晶体模型的专题讨论会。

NONTECHNICAL SUMMARYThe Division of Materials Research and the Division of Mathematical Sciences contribute funds to this award. It supports interdisciplinary research and educational activities in computational materials science, with a focus on the growth of two-dimensional (2D) semiconducting materials. While graphene is the best-known 2D material, it is limited in device application due to its high conductivity. More recent research has focused on 2D semiconducting materials, which can be manipulated to block or permit current flow. These research activities have been primarily based on experimental explorations due to a gap in the fundamental understanding in what determines their structures and properties. This project aims to help fill this gap by developing a model for the growth of these systems based on the phase field crystal modeling approach. This approach allows researchers to study materials involving tiny structures as small as atoms. The team of researchers will develop, parameterize, and validate a phase field crystal model for 2D semiconducting materials, which can be used improve the synthesis process of 2D materials and their assembly. Simulations will also be used to examine the structure of these materials and associated defects at the atomic level. Educational activities include courses on crystal growth for high school students, proposed as part of the California State Summer School for Mathematics and Science at UC Irvine, engaging with Science Olympiad, and other STEM events. These activities will help develop the future generation of mathematicians, scientists and engineers. Graduate students will receive interdisciplinary training and will present their findings at conferences, which will enhance their educational experience. The team shall also act as a resource for the research community by distributing the codes that are developed and by organizing symposia on phase field crystal models at national meetings.TECHNICAL SUMMARYThe Division of Materials Research and the Division of Mathematical Sciences contribute funds to this award. It supports interdisciplinary research and educational activities in computational materials science, with a focus on the growth of two-dimensional (2D) semiconducting materials. The recent discovery of two-dimensional (2D) semiconducting materials such as MoS2 and MoSe2 has intensified the research efforts in these materials. These materials exhibit unique properties due to the 2D confinement, but they, unlike graphene, also possess the ability to switch between conducting and insulating states, offering a potential to yield revolutionary new technologies. The research efforts have been primarily based on experimental exploration based on various synthetic routes, and significant gaps exist in the fundamental understanding of what determine their bulk and defect structures and morphologies, as well as how they influence their properties. Due to the small length scale involved, computational modeling is essential for developing such understanding. Phase field crystal (PFC) modeling is uniquely suited for this problem because of its ability to resolve atomic-scale structure and its extended time-scale comparable to those associated with synthesis. This multidisciplinary project addresses the challenge of understanding multiscale phenomena associated with the formation of nanostructures by exploiting recent developments in PFC models, which follow the dynamics of individual atoms over diffusive time scales. Originating from classical density functional theory, the PFC method naturally incorporates elastic and plastic deformations as well as crystalline defects. The team of materials scientists and a mathematician will develop a new PFC-based computational methodology for modeling the structure and the synthesis of two-dimensional, multicomponent materials. The models will be parameterized and validated with the aid of atomistic simulations and experimental results. Defects such as grain boundaries, which must be controlled in device applications, will be examined. The computational tools will build on the efficient numerical algorithms developed under previous funding and tailor it to the new models and will be disseminated through repositories such as GitHub. These tools will provide a framework for the computational discovery of the fundamental mechanisms underlying synthesis of 2D materials, their assembly, and their atomic-scale structure. Educational activities include courses on crystal growth for high school students, proposed as part of the California State Summer School for Mathematics and Science at UC Irvine, engaging with the Science Olympiad, and other STEM events. These activities will help develop the future generation of mathematicians, scientists and engineers. Graduate students will receive interdisciplinary training and will present their findings at conferences, which would enhance their educational experience. The group shall also act as a resource for the research community by organizing symposia on phase field crystal models at national meetings.