Ab Initio Calculations in Correlated Electron Models and Materials

该奖项支持计算和理论研究和教育活动，以提高我们对材料性能的理解和计算能力。 在由许多粒子组成的量子系统中进行精确和预测性的计算是科学界的一个巨大挑战。在这些系统中，相互竞争的趋势的微妙平衡创造了物质和集体现象的新阶段的丰富可能性，这提供了具有重大技术重要性的显着材料特性的潜力。然而，这种丰富性和复杂性也意味着通常的定量计算工具将趋于崩溃。 方法的发展和高性能计算的出现相结合，提出了一个前所未有的机会，使这个问题的根本进展。该研究将建立在量子多粒子模拟方法的最新进展基础上，为催化这一进展贡献独特的组成部分。该研究旨在推进具有强电子-电子相互作用的材料的研究，建立准确的基准计算，并增强凝聚态系统中直接，多粒子无参数计算的能力。该项目的理论框架和技术也可以在核物理、超冷原子物理和量子化学领域产生交叉影响。PI将继续将研究与教育和外联活动相结合，指导本科生和研究生进行研究，将该项目的材料纳入课程，接触少数民族学生，促进计算科学教育和研究的跨学科合作。 在更大的科学界，PI将继续发挥积极作用，通过学校和讲习班培训学生，博士后和高级研究人员，并开发软件包和教程的手-在学习新的理论和计算方法和强相互作用电子系统的属性。技术总结该奖项支持的应用和进一步发展的研究和教育活动，相关电子系统中的量子场蒙特卡罗及相关计算方法。该研究计划的长期目标是能够进行多体模拟，以更准确和预测的方式解决结构相变，磁序和超导性问题。将对真实的材料进行具体材料计算，并对简化模型进行研究。将开发新的能力来扩展可以处理的系统尺寸，进一步提高精度，计算激发态和响应特性，以及处理自旋-轨道耦合。在相互作用的多费米子系统的计算机模拟中，主要的困难是符号或相位问题。约束路径或无相量子场蒙特卡罗方法为从头计算材料模拟（作为超越标准密度泛函计算的方法）和强关联系统的晶格模型计算提供了一个通用框架。预计开发的成功将影响到正在研究的特定系统之外。PI将继续将研究与教育和推广活动相结合，指导本科生和研究生进行研究，将该项目的材料纳入课程，接触少数民族学生，并促进计算科学教育和研究的跨学科合作。 在更大的科学界，PI将继续通过学校和研讨会在培训学生，博士后和高级研究人员方面发挥积极作用，并开发软件包和教程，用于实践学习新的理论和计算方法以及强相互作用电子系统的特性。

NON-TECHNICAL SUMMARYThis award supports computational and theoretical research and education activities to advance our understanding of and capabilities to compute materials properties. Accurate and predictive calculations in quantum systems composed of many particles are a grand challenge in science. In these systems the delicate balance of competing tendencies creates rich possibilities of new phases of matter and collective phenomena, which offer the potential for remarkable material properties of great technological importance. This very richness and complexity, however, also means that the usual tools for quantitative calculations will tend to break down. The combination of methodological developments and the advent of high performance computing present an unprecedented opportunity to make fundamental progress in this problem now. The research will build on recent advances in a quantum many-particle simulation approach to contribute a unique component for catalyzing this progress.This research aims to advance the study of materials with strong electron-electron interactions, establish accurate benchmark calculations, and enhance the capabilities of direct, many-particle parameter-free computations in condensed matter systems. The theoretical framework and techniques developed can also have cross-cutting impact in nuclear physics, ultracold atom physics, and quantum chemistry.The PI will continue to integrate research with education and outreach activities, by mentoring both undergraduate and graduate students in research, incorporating materials from this project into courses, reaching out to minority students, and fostering interdisciplinary collaboration in computational science education and research. In the larger scientific community, the PI will continue to play an active role in training students, post-docs, and senior researchers through schools and workshops, and develop software packages and tutorials for hands-on learning of new theoretical and computational approaches and the properties of strongly interacting electron systems.TECHNICAL SUMMARYThis award supports research and educational activities on the application and further development of the auxiliary-field quantum Monte Carlo and related methods for calculations in correlated electron systems. The long-term goal of this research program is the ability to perform many-body simulations to address questions on structural phase transitions, magnetic order, and superconductivity in a more accurate and predictive manner. Both materials-specific calculations on real materials and the study of simplified models will be conducted. New capabilities will be developed to extend the system sizes that can be treated, further improve accuracy, compute excited state and response properties, and treat spin-orbit coupling.The leading difficulty in computer simulations of interacting many-fermion systems is the sign or phase problem. The constrained path or phase-free auxiliary-field quantum Monte Carlo approach provides a general framework for both ab initio materials simulations (as an approach to go beyond standard density-functional calculations) and for calculations in lattice models of strongly correlated systems. Success in the development can be expected to impact beyond the specific systems being studied. The PI will continue to integrate research with education and outreach activities, by mentoring both undergraduate and graduate students in research, incorporating materials from this project into courses, reaching out to minority students, and fostering interdisciplinary collaboration in computational science education and research. In the larger scientific community, the PI will continue to play an active role in training students, post-docs, and senior researchers through schools and workshops, and develop software packages and tutorials for hands-on learning of new theoretical and computational approaches and the properties of strongly interacting electron systems.