Theoretical Solid State Physics

非技术总结该奖项支持理论和计算研究和教育，目的是在微观层面上了解材料和纳米结构的电子、光学和磁性，预测新材料和现象，并为这一领域的研究培养年轻科学家。凝聚态物质的迷人性质和现象源于构成物质的电子和离子的相互作用。了解这些相互作用是现代技术的核心，例如电子学、光电子学、光伏和一般的能量转换设备。通过改变化学成分、将材料限制在纳米尺度或在一维或二维水平上探索材料，这些属性可以显著改变，新的现象可能会出现。这个项目的中心是使用量子理论、建模和模拟，使用分析和计算工具来解释和预测新材料和纳米结构的存在和性质。新的理论方法和现代高性能计算机的可用性使该团队能够获得材料行为的第一性原理(即，没有经验参数)的解释和预测，包括原子薄材料、纳米结构、界面和缺陷现象、新超导体和光催化材料。教育部分的重点是为学生(研究生和本科生)和博士后研究员在当前的量子技术革命中进行研究和开发做好准备。从该项目开发的计算工具将被合并到几个软件包中，这些软件包可在网上免费向研究界提供。另一项教育活动与公共教育有关，这是通过在非专业媒体上发表文章和采访，以及通过国际和平协会和联合国际的公开讲座来完成的。技术总结该奖项支持理论和计算研究和教育，通过执行第一原理量子计算，在微观层面上了解材料和纳米结构的电子、运输、光学和磁性。这项研究分为凝聚态物理和材料科学的三个热门领域：1)材料的新相和新结构；2)降维系统的光学和自旋物理；3)电子-声子耦合、光-物质相互作用和超导。主要目标是使用多体量子理论、高性能计算和拓扑学等新概念来解释和预测真实材料的性质和现象，包括低维系统。基于多体量子理论的几种最先进的方法被用来实现对真实材料的准确的第一原理计算。基态性质是用从头算赝势密度泛函理论形式得到的。通过光学性质的Bethe-Salpeter方程，计算了准粒子激发的GW近似下相互作用的单粒子格林函数和相互作用的两粒子格林函数的激发态性质。用基于GW微扰理论的新方法计算了电子-声子耦合。用另一种新发展的含时绝热GW方法计算了驱动场和非线性光学响应下的含时现象。上面的方法显示了许多属性都可以访问。例子包括结构信息、电子结构、能隙、光学和光电子能谱、电子拓扑不变量、表面和界面特征、振动和机械性质、磁性、输运性质、泵浦-探测光谱、非线性光学响应以及传统超导体的性质。还进行了理论和方法的发展，以进一步提高我们的概念和计算能力。第一原理计算在适当的时候用模型哈密顿研究来补充，特别是为了理解拓扑效应和具有更强电子关联的系统。教育部分侧重于培养学生(研究生和本科生)和博士后研究员在当前的量子技术革命中进行研究和开发。从该项目开发的计算工具将被合并到三个开源软件包--Berkeley GW、PARATEC和EPW中，这些软件包可以在网上免费向社区提供。另一项教育活动与公众教育有关，这是通过在非专业媒体上发表文章和采访，以及通过PI和共同PI的公开演讲来完成的。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NONTECHNICAL SUMMARYThis award supports theoretical and computational research and education with the goals of understanding the electronic, optical, and magnetic properties of materials and nanostructures at the microscopic level, predicting new materials and phenomena, and educating young scientists for research in this field. The fascinating properties and phenomena of condensed matter emerge from mutual interactions of the electrons and ions that make up materials. Understanding these interactions are central to modern technologies such as electronics, optoelectronics, photovoltaics, and energy conversion devices in general. These properties can be dramatically altered, and new phenomena can emerge, by varying the chemical composition or confining the materials to nanometer scales or exploring materials at the one- or two-dimensional level. This project is centered on using quantum theory, modeling, and simulations using analytical and computational tools to explain and predict the existence and properties of novel materials and nanostructures. New theoretical approaches and the availability of modern high-performance computers allow the team to obtain first-principles (i.e., with no empirical parameters) explanations and predictions of the behavior of materials including atomically thin materials, nanostructures, interfacial and defect phenomena, new superconductors, and photocatalytic materials. The educational component is focused on preparing students (graduate and undergraduate) and postdoctoral fellows for research and development in the current quantum technological revolution. The computational tools developed from the project will be incorporated into several software packages, which are made freely available on the web to the research community. Another educational activity is related to public education, which is done through articles and interviews published in lay media and via public lectures by the PI and co-PI. TECHNICAL SUMMARYThis award supports theoretical and computational research and education towards understanding the electronic, transport, optical, and magnetic properties of materials and nanostructures at the microscopic level by performing first-principles quantum calculations. The research is grouped into three topical areas of condensed matter physics and materials science: 1) novel phases and structures of materials; 2) optical and spin physics of reduced-dimensional systems, and 3) electron-phonon coupling, light-matter interaction, and superconductivity. The major objective is to use many-body quantum theory, high-performance computing, and new concepts such as those from topology to explain and predict the properties of and phenomena in real materials, including lower dimensional systems. Several state-of-the-art approaches based on many-body quantum theory are employed to enable accurate first-principles calculations for real materials. Ground-state properties are obtained using the ab initio pseudopotential density functional theory formalism. Excited-state properties are calculated from the interacting one-particle Green's function within the GW approximation for quasiparticle excitations and the interacting two-particle Green's function via the Bethe-Salpeter equation for optical properties. Electron-phonon couplings are computed using a new methodology based on GW perturbation theory. Time-dependent phenomena under driven fields and nonlinear optical responses are computed using another newly developed time-dependent adiabatic GW method. A host of properties are shown to be accessible with the above methods. Examples include structural information, electronic structure, energy gaps, optical and photoemission spectra, electronic topological invariants, surface and interface characteristics, vibrational and mechanical properties, magnetic properties, transport properties, pump-probe spectroscopies, nonlinear optical responses, and properties of conventional superconductors. Theoretical and methodological developments are also carried out to further advance our conceptual and computational capabilities. The first-principles calculations are augmented with model Hamiltonian studies when appropriate, especially for understanding topological effects and systems with stronger electron correlations.The educational component is focused on training of students (graduate and undergraduate) and postdoctoral fellows for research and development in the current quantum technological revolution. The computational tools developed from the project will be incorporated into three open-source software packages - Berkeley GW, PARATEC, and EPW - which are freely available to the community on the web. Another educational activity is related to public education, which is done through articles and interviews published in lay media and via public lectures by the PI and co-PI.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.