CAREER: Correlated excited states of point defects in insulators

非技术性总结该奖项支持旨在了解材料中局部缺陷（称为“点缺陷”）特性的计算研究和教育活动，例如原子从其通常位置丢失或材料中的杂质。这种点缺陷普遍存在于所有材料中，即使存在极少量，也会对其性能产生深远影响。在电子设备的背景下，点缺陷可能是有害的，例如，降低太阳能电池的效率;或功能性的，例如，允许材料的性质被调整。缺陷本身甚至可以用作下一代量子计算机的微小量子比特。点缺陷的小而稀的性质使它们对实验表征具有挑战性，因此计算模拟至关重要。然而，传统的计算方法对于关键缺陷性质具有有限的准确性，包括它们对外部刺激（如光或电脉冲）的响应。更先进的理论具有更好的精度，但需要太多的计算能力，以应用于点缺陷。该项目旨在开发和利用通过"嵌入"克服这些问题的计算工具，即，通过将传统方法与先进理论相结合，以获得计算效率和精度。这些新技术将使PI和他的团队能够对外部刺激激发的复杂缺陷进行前所未有的理解。PI将应用这些嵌入方法来探索各种缺陷和宿主材料，这些材料有望用于包括量子计算机在内的下一代电子设备。该奖项还支持各级计算物理教育的发展。在研究生一级，将专门开设一门课程，讲授计算凝聚态物理学的最新方法;在本科一级，将修改物理专业必修的计算物理课，使其更具互动性和项目性;在高中阶段，该奖项支持旨在理解物理学的研究和教育活动，点缺陷的激发电子态。PI将开发量子嵌入技术，用于结合密度泛函理论和多体方法，以准确捕获电子相关性和电子设备和量子技术相关缺陷中的激发。旨在改进方法的项目将开发更准确和更强大的缺陷轨道之间的库仑相互作用、缺陷和体相态之间的杂交以及密度泛函理论与多体方法相结合的双重计算本质的处理方法。与其他基于量子蒙特卡罗的多体方法的比较将进行基准的嵌入过程中所涉及的各种近似。此外，PI将专注于涉及缺陷和晶格之间的相互作用的问题，以确定相关的激发态在缺陷的光学和非辐射过程中的作用。目标缺陷/宿主系统将包括六方BN中的碳基缺陷、III族氮化物中的过渡金属以及过渡金属二硫属化物中的稀土，所有这些都对传统和量子电子器件具有基础和技术意义。该奖项还支持各级计算物理教育的发展。在研究生一级，将专门开设一门课程，讲授计算凝聚态物理学的最新方法;在本科一级，将修改物理专业必修的计算物理课，使其更具互动性和项目性;在高中阶段，该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识产权进行评估来支持。优点和更广泛的影响审查标准。

NONTECHNICAL SUMMARYThis award supports computational research and education activities that aim to understand the properties of localized imperfections in materials, called "point defects", such as atoms missing from their usual locations or impurities within the material. Such point defects are ubiquitous in all materials and can have profound effects on their properties even if present in minute quantities. In the context of electronic devices, point defects may be detrimental, e.g., lowering the efficiency of solar cells; or functional, e.g., allowing the properties of materials to be tuned. Defects themselves can even be used as tiny quantum bits for next generation quantum computers. The small and dilute nature of point defects makes them a challenge for experimental characterization, thus computational simulations are vital. However, conventional computational methods have limited accuracy for key defect properties including their response to external stimuli like light or electrical pulses. More advanced theories with significantly better accuracy exist but require too much computational power to be applied to point defects. This project seeks to develop and utilize computational tools that overcome these issues via “embedding,” i.e., by combining the conventional methods with the advanced theories to obtain both computational efficiency and accuracy. These new techniques will allow the PI and his team to develop unprecedented understanding of complex defects excited by external stimuli. The PI will apply these embedding methods to explore a variety of defects and host materials that are promising for the next generation electrical devices including quantum computers.This award also supports the development of computational physics education at all levels. At the graduate level, a course specifically aimed at teaching state-of-the-art methods in computational condensed-matter physics will be developed; at the undergrad level, the computational physics class required for physics majors will be altered to make it more interactive and project-based; and at the high-school level, outreach will be conducted to improve computational literacy.TECHNICAL SUMMARYThis award supports research and educational activities that aim to understand the physics of excited electronic states of point defects. The PI will develop quantum embedding techniques for combining density-functional theory and many-body methods to accurately capture electron correlations and excitations in defects relevant for electronic devices and quantum technologies. Projects aimed at methodological improvements will develop more accurate and robust treatments of Coulomb interactions between defect orbitals, hybridization between the defect and bulk states, and the double-counting intrinsic to combining density-functional theory with many-body methods. Comparisons with other many-body methods based on quantum Monte Carlo will be performed to benchmark the various approximations involved in the embedding procedure. In addition, the PI will focus on problems involving interplay between the defect and the crystal lattice to determine the role of correlated excited states in optical and nonradiative processes at defects. The specific defect/host systems targeted will include carbon-based defects in hexagonal BN, transition metals in group-III nitrides, and rare earths in transition-metal dichalcogenides, all of which are of fundamental as well as technological interest for conventional and quantum electronic devices.This award also supports the development of computational physics education at all levels. At the graduate level, a course specifically aimed at teaching state-of-the-art methods in computational condensed-matter physics will be developed; at the undergrad level, the computational physics class required for physics majors will be altered to make it more interactive and project-based; and at the high-school level, outreach will be conducted to improve computational literacy.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.