Collaborative Research: Petascale Simulations of Quantum Systems by Stochastic Methods: Tools and Applications

合作研究：通过随机方法对量子系统进行千万亿次模拟：工具和应用

• 批准号: 0904794
• 负责人: Lubos Mitas
• 金额: $ 47.89万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0904794&HistoricalAwards=false
• 关键词: Collaborative; Research; Petascale; Simulations; Quantum

TECHNICAL SUMMARY This award supports developing, testing, and optimizing a new generation of simulation codes for calculating electronic states on petascale computers. The codes will be based on quantum Monte Carlo methods. The effort will combine recent advances in computer science, such as Global Arrays, fault-tolerant parallelism, Graphics Processing Units and task-dynamical parallelism, with recent disciplinary advances that can treat correlated electronic systems and study physical effects currently out of reach. The goal is to establish production-quality quantum Monte Carlo codes that can exploit Track I and follow-on hardware to achieve scientific breakthrough calculations. Successful use of petascale computers will likely be very challenging. Scaling up the quantum Monte Carlo codes by more than two orders of magnitude will require pursuing new avenues for algorithm organization and parallelization; for example, utilizing the multicore/shared memory nature of the nodes. Attention to fault tolerance and load balance will lead to reliable and efficient petascale codes. A key thrust will be to couple quantum Monte Carlo methods for electrons with classical simulation methods for the ions enabling realistic simulations on virtually any system. New predictive capabilities and insights will result, particularly into dynamics and finite temperature phenomena using a full quantum mechanical description of the electrons. Another thrust involves applying quantum Monte Carlo to strongly correlated electronic systems - among the most important challenges in condensed matter physics. The PIs plan to implement and test new correlated wavefunctions such as pfaffians with backflow, and new quantum Monte Carlo algorithms, such as the dynamical coupling of classical and quantum degrees of freedom. These developments will be applied to study water with a full quantum mechanical description of all the relevant degrees of freedom such as electrons and protons at nonzero temperatures without any empirical or mean-field inputs. Quantum Monte Carlo calculations will also be used to understand transition metal compounds, in particular, the magnetic states and metal-insulator transitions at high pressures in transition metal oxide materials. Despite decades of studies these systems remain inadequately understood and require exceedingly high accuracy to reveal the origins of a variety of many-body phenomena and experimentally observed phenomena. The developed computational tools will be available to the scientific community through the open source projects QMCPACK, and QWalk. The Global Arrays toolkit will provide a high-level and scalable programming environment based on the global address space programming model. This research and development effort will also support training of graduate students and postdocs in the area of high performance computing. The PIs will organize a Summer School, "Petaflop Quantum Monte Carlo Methods," to train students, postdocs and researchers in the developed methodologies and enable them to open new frontiers with high performance computing at the petascale and beyond. NONTECHNICAL SUMMARY This award supports developing, testing, and tuning the performance of a new generation of computer codes targeted for the most powerful computers. These new codes will be based on quantum mechanics and create a "virtual microscope" that probe materials at the atomic scale. These codes will provide an accurate determination of the forces between atoms enabled by an accurate quantum mechanical description of the electrons and their motions which are the ultimate sources of these forces. The resulting code will be applied to study water, perhaps the most important component of life but also one of the most challenging liquids and solids to understand. The accurate description of electrons afforded by the PIs codes will enable the most accurate computational study of materials which involve electrons that interact strongly with each other leading to new states of matter. Understanding these materials may lead to the discovery of new states of matter that may lead to new materials and device technologies. The codes that are developed will be made available to the broader computational community of scientists and empower them to utilize the most powerful computers to open new frontiers. This research and development effort will also support training of graduate students and postdocs in the area of high performance computing. The PIs will organize a Summer School, "Petaflop Quantum Monte Carlo Methods," to train students, postdocs and researchers in the developed methodologies and enable them to open new frontiers with high performance computing at the petascale.

该奖项支持开发，测试和优化新一代模拟代码，用于在千万亿次计算机上计算电子状态。这些代码将基于量子蒙特卡罗方法。这项工作将结合联合收割机在计算机科学的最新进展，如全球阵列，容错并行，图形处理单元和任务动态并行，与最近的学科进展，可以治疗相关的电子系统和研究目前无法达到的物理效应。目标是建立生产质量的量子蒙特卡罗代码，可以利用Track I和后续硬件实现科学突破性计算。成功地使用千万亿次计算机可能是非常具有挑战性的。将量子蒙特卡罗码放大两个数量级以上将需要寻求算法组织和并行化的新途径;例如，利用节点的多核/共享内存特性。注意容错和负载平衡将导致可靠和有效的千万亿次代码。一个关键的推力将是耦合量子蒙特卡罗方法的电子与经典的模拟方法的离子，使现实的模拟几乎任何系统。新的预测能力和见解将导致，特别是到动力学和有限的温度现象使用完整的量子力学描述的电子。另一个重点是将量子蒙特卡罗应用于强关联电子系统-凝聚态物理学中最重要的挑战之一。PI计划实现和测试新的相关波函数，如具有回流的pfavorans，以及新的量子蒙特卡罗算法，如经典和量子自由度的动态耦合。这些发展将被应用于研究水与所有相关的自由度，如电子和质子在非零温度下没有任何经验或平均场输入的完整的量子力学描述。量子蒙特卡罗计算也将用于理解过渡金属化合物，特别是过渡金属氧化物材料在高压下的磁性状态和金属-绝缘体转变。尽管几十年的研究，这些系统仍然没有得到充分的理解，并需要非常高的精度来揭示各种多体现象和实验观察到的现象的起源。开发的计算工具将通过开源项目QMCPACK和QWalk提供给科学界。全局阵列工具包将提供一个基于全局地址空间编程模型的高级和可扩展的编程环境。这项研究和开发工作还将支持高性能计算领域的研究生和博士后的培训。PI将组织一个暑期学校，“Petaflop量子蒙特卡罗方法”，以培训学生，博士后和研究人员在开发的方法，并使他们能够打开新的前沿与高性能计算在petascale和超越。该奖项支持开发，测试和调整针对最强大计算机的新一代计算机代码的性能。这些新代码将基于量子力学，并创建一个“虚拟显微镜”，在原子尺度上探测材料。这些代码将提供对原子之间的力的精确确定，这是通过对电子及其运动的精确量子力学描述实现的，电子及其运动是这些力的最终来源。由此产生的代码将用于研究水，水可能是生命中最重要的组成部分，但也是最具挑战性的液体和固体之一。PI代码所提供的电子的准确描述将使材料的最准确的计算研究成为可能，这些材料涉及相互强烈相互作用的电子，从而导致新的物质状态。了解这些材料可能会导致发现新的物质状态，从而可能导致新的材料和设备技术。开发的代码将提供给更广泛的科学家计算社区，使他们能够利用最强大的计算机来开辟新的领域。这项研究和开发工作还将支持高性能计算领域的研究生和博士后的培训。PI将组织一个暑期学校，“Petaflop量子蒙特卡罗方法”，以培训学生，博士后和研究人员在开发的方法，并使他们能够打开新的前沿与高性能计算在千万亿次。