NSF/DMR-BSF: Density Functionals for Predictive Excited-State Calculations of Solids

美国国家科学基金会和美国-以色列两国科学基金会（BSF）共同支持一名美国研究人员和一名以色列研究人员之间的合作。该奖项由美国国家科学基金会（NSF）材料研究部门资助，旨在支持先进的模拟和预测材料性能的计算方法的研究和教育。由于对材料如何收集光、传导能量和传输电荷没有详细的了解，将太阳光转化为电能的新材料的发现和开发受到了极大的限制。所有这些现象都是计算模型的挑战，因为它们涉及激发态。现有的计算方法对这些过程具有预测能力，但它们的计算成本很高。开发计算效率更高的替代方法，提供类似的准确性，将使预测日益复杂的材料成为可能，并将有助于将这些方法用于材料的发现和设计。该研究项目为开发这种对真实材料有效的预测方法奠定了重要的基础。该计划的核心工作是拓展和指导所有年龄段的下一代计算材料理论家，并有针对性地招募女性和其他代表性不足的少数族裔本科生和研究生。PI还将为湾区及其他地区的本科生、小学生、中学生以及教育工作者组织参观当地的研究设施。这些在美国的研究生将前往以色列，在以色列PI的小组进行研究。美国国家科学基金会和美国-以色列双国家科学基金会（BSF）共同支持一名美国研究人员和一名以色列研究人员之间的合作。该奖项由美国国家科学基金会（NSF）材料研究部门资助，旨在支持先进的模拟和预测材料性能的计算方法的研究和教育。在材料和凝聚态物理中，长期以来选择多体微扰理论作为定量确定能带结构的形式。这种形式已经为许多不同类别的金属、半导体和绝缘体提供了出色的电子结构预测。然而，这些预测需要大量的计算成本；基于Kohn-Sham方程解得到的单电子能量和轨道，从密度泛函理论（DFT）中提取能带结构可以减轻这一成本。该项目涉及两国理论和计算合作，以开发一类新的密度泛函-最佳调谐范围分离杂化（OTRSH）泛函-能够预测精确的准粒子带隙和带结构，以及光学光谱，包括电子-空穴相互作用，用于一系列复杂的固态材料，具有比现有方法更高的计算效率。使用一组经过充分研究的基准材料，该团队将：i)确定范围分离参数，使每种化合物的OTRSH和前沿激发态方法之间达到最佳匹配；Ii)发展距离分离参数的物理特性；iii)推进OTRSH方法。然后，研究团队将OTRSH方法应用于一系列当代感兴趣的复杂系统，包括过渡金属氧化物、狄拉克材料、卤化物钙钛矿和二维材料。该研究活动还将系统地解决几个悬而未决的问题，并最终开发一种有效的DFT方法来理解复杂材料中现有的和预测新的激发态现象。该计划的核心工作是拓展和指导所有年龄段的下一代计算材料理论家，并有针对性地招募女性和其他代表性不足的少数族裔本科生和研究生。PI还将为湾区及其他地区的本科生、小学生、中学生以及教育工作者组织参观当地的研究设施。这些在美国的研究生将前往以色列，在以色列PI的小组进行研究。

NONTECHNICAL SUMMARYThe National Science Foundation and the United States -- Israel Binational Science Foundation (BSF) jointly support this collaboration between a US-based researcher and an Israel-based researcher. The NSF Division of Materials Research funds this award, which supports research and education on the development of advanced computational methods for the simulation and prediction of materials properties.The discovery and development of new materials for converting sunlight into electricity is significantly limited by not having detailed understanding of how materials harvest light, transduce energy, and transport electric charge. All these phenomena are a challenge to model computationally as they involve excited electronic states. There exist computational methods with predictive power for such processes, but they come at significant computational cost. Developing more computationally efficient alternative approaches that offer similar accuracy would enable predictions for increasingly complex materials and would facilitate adapting such methods for materials discovery and design. This research project lays important groundwork toward the development of such efficient predictive approaches for real materials. Central to the proposed effort is outreach to and mentoring of next-generation computational materials theorists at all age levels, augmented by targeted recruitment of women and other underrepresented-minority undergraduate and graduate students. The PI will also organize tours of local research facilities for undergraduate, elementary, and middle-school students - as well as educators - in the Bay area and beyond. The US-based graduate students will travel to Israel to carry out research at the Israeli PI's group.TECHNICAL SUMMARYThe National Science Foundation and the United States -- Israel Binational Science Foundation (BSF) jointly support this collaboration between a US-based researcher and an Israel-based researcher. The NSF Division of Materials Research funds this award, which supports research and education on the development of advanced computational methods for the simulation and prediction of materials properties.In materials and condensed matter physics, the formalism of choice for quantitative determination of the band structure has long been many-body perturbation theory. This formalism has yielded excellent electronic structure predictions for many different classes of metals, semiconductors, and insulators. However, these predictions come at significant computational cost; extracting band structures from density functional theory (DFT), based on the single-electron energies and orbitals obtained from the solution of the Kohn-Sham equation, could alleviate this cost. The project involves a binational theoretical and computational collaboration to develop a new class of density functionals - optimally tuned range-separated hybrid (OTRSH) functionals - capable of predicting accurate quasiparticle band gaps and band structures, and optical spectra, including electron-hole interactions, for a range of complex solid-state materials, with greater computational efficiency than existing approaches. Using a benchmark set of well-studied materials, the team will: i) determine range-separation parameters that lead to the best match between OTRSH and the leading-edge excited-state method for each of these compounds; ii) develop the physics of the range-separation parameters; and iii) advance the OTRSH approach. The research team will then apply the OTRSH approach to a range of complex systems of contemporary interest, including transition metal oxides, Dirac materials, halide perovskites, and two-dimensional materials. The research activity will also address several open questions systematically, and ultimately develop an efficient DFT approach for understanding existing and predicting new excited-state phenomena in complex materials.Central to the proposed effort is outreach to and mentoring of next-generation computational materials theorists at all age levels, augmented by targeted recruitment of women and other underrepresented-minority undergraduate and graduate students. The PI will also organize tours of local research facilities for undergraduate, elementary, and middle-school students - as well as educators - in the Bay area and beyond. The US-based graduate students will travel to Israel to carry out research at the Israeli PI's group.