RII Track-4: Big Data and Massive Computation Approaches to Non-Equilibrium Dynamics of Strongly Correlated Materials

在一些材料中，电子在材料结构中的运动可以是高度相关的，例如电子的行为就像汽车在拥挤的交通中移动；他们不能自由活动，他们的动作受到他人的强烈影响。表现出电子相关性的材料也表现出有趣的特性，比如金属绝缘体跃迁和非常规的超导性。然而，电子相关是否是这些观察到的效应的唯一原因，几十年来一直困扰着科学家。克服这一知识上的差距将为新型晶体管和超快器件的应用带来革命性的机遇。在这个项目中，PI将使用橡树岭国家实验室的超级计算能力来解决这个具有挑战性的问题。先进的模拟将使用数以万计的计算处理器来模拟原子尺度上电子相关系统的行为。该研究将产生超过100tb的数据，需要使用大数据技术来有效地处理和分析庞大的数据量。该项目包括努力扩大下一代科学计算劳动力的参与。研究主题涉及美国国家科学基金会未来投资的10大理念和基础能源科学的重大挑战中的几个，因此也对美国的科学领导和能源可持续发展的未来产生潜在影响。技术描述该项目的重点是模拟远离平衡的量子多体现象，目的是了解在超短时间尺度上时域光谱揭示的相关电子的非平衡行为。超过1000亿个基态的矩阵对角化将通过无矩阵和数据流计算来解决。基于平衡和非平衡波函数的量子杂质求解器也将被开发。为了减少时间演化计算的计算成本，将进一步实现非线性时间序列回归。利用有效的单波段哈伯德模型和来自万尼尔投影的多轨道哈密顿量，将所得代码用于模拟二氧化钒（VO2）的超快光子光谱。结构跃迁的作用将通过限制声子计算来解决。这些模拟可以显著地促进对VO2和其他强相关过渡金属氧化物的非平衡现象和光致相变的理解。开源软件也将免费提供给公众用于并行云计算，以进一步有利于科学界对非平衡多体问题的数值研究。

Non-technical DescriptionIn some materials, the motion of elections through the material structure can be highly correlated, such that the electrons behave as cars move in heavy traffic; they cannot maneuver freely and their motions are strongly influenced by others. Materials that exhibit electron correlations also exhibit intriguing properties, such as metal-insulator transitions and unconventional superconductivity. However, whether electron correlation is the sole cause of these observed effects has perplexed scientists for decades. Overcoming this gap in knowledge could open up revolutionary opportunities for novel transistor and ultrafast device applications. In this project, the PI will use the supercomputing capabilities at Oak Ridge National Laboratory to tackle this challenging problem. Advanced simulations will be performed using tens of thousands of computing processors to model the behavior of electron correlation systems at the atomic scale. The research will generate more than 100 terabytes of data, requiring that Big Data techniques be employed to effectively process and analyze the huge data volume. The project includes efforts to broaden participation in the next-generation scientific computing workforce. The research topics address several of the 10 Big Ideas for Future NSF Investments and the Grand Challenges in Basic Energy Sciences, thereby also having potential impacts on U.S. science leadership and an energy-sustainable future.Technical DescriptionThe project's focus is on modeling quantum many-body phenomena driven away from equilibrium, with the goal of understanding correlated electrons' non-equilibrium behaviors revealed by time-domain spectroscopies at ultra-short time scales. Matrix diagonalization over 100 billion basis states will be tackled by matrix-free and dataflow computing. Equilibrium and non-equilibrium wavefunction-based quantum impurity solvers also will be developed. Non-linear time series regression will be further implemented to alleviate the computational cost for time-evolution calculations. The resulting codes will be employed to simulate ultrafast photon-based spectroscopies on vanadium dioxide (VO2), using effective single-band Hubbard model and multi-orbital Hamiltonian from Wannier projection. The role of structure transition will be addressed by restricted phonon calculations. These simulations could significantly advance the understanding of non-equilibrium phenomena and photo-induced phase transitions in VO2 and other strongly correlated transition-metal oxides. Open-source softwares also will be made freely available to the public for parallel cloud computing to further benefit the scientific community for numerical studies of non-equilibrium many-body problems.