Fluctuation-Based Electronic Structure Methods

加州大学欧文分校的Filipp Furche获得了化学系化学理论、模型和计算方法项目的奖励，以开发、实施、测试和应用新的计算化学方法。材料研究部的凝聚态物质和材料理论项目也为该奖项做出了贡献。新方法可以模拟分子和凝聚态物质系统，这些系统很难用传统方法处理，例如用于催化的稀土化合物或过渡金属化合物。这些系统对科学和新兴技术至关重要。Furche提出的基于量子涨落的电子结构理论的一种完全不同的方法有望克服许多这些限制。该项目开发的方法通过Turbomole量子化学软件向公众开放。该项目通过在UCI开设理论和计算化学的新专业，以及针对弱势背景学生的高中外展计划，提高了本科教育和劳动力准备水平。Furche和他的团队正在开发新的方法来预测分子和凝聚态系统，如小带隙或相关材料和簇，非共价结合的纳米结构，或过渡金属和稀土化合物的光学性质。尽管它们对科学和新兴技术至关重要，但由于精度不足、计算效率不足或两者兼而有之，这些系统与传统的电子结构方法相比仍然几乎难以处理。随机相位近似（RPA）方法在之前的资助期间发展是基于波动的电子结构理论的原型。在RPA的成功和失败的指导下，Furche和他的团队正在为基于波动的电子结构方法的系统改进层次奠定基础。与化学中基于相互作用的电子对、三元组等的电子相关的传统方法相反，本文提出的方法通过由电子和空穴的虚对（及其倍数）在时间上向前和向后运动所产生的真空波动来描述多电子系统中的相关。Furche和他的团队还探索了一个Brueckner函数框架，作为Kohn-Sham参考状态的替代方案，并旨在将RPA方法的范围扩展到电离、时间相关性质和激发态。应用包括低价稀土和锕系化合物，以及卤素- π相互作用介导的药物设计。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Filipp Furche of the University of California, Irvine is supported by an award from the Chemical Theory, Models and Computational Methods Program in the Division of Chemistry to develop, implement, test, and apply novel computational chemistry methods. The Condensed Matter and Materials Theory program in the Division of Materials Research also contributes to this award. The new methods enable simulations of molecules and condensed matter systems that are very difficult to treat with conventional approaches, for example rare-earth compounds or transition metal compounds used in catalysis. Such systems are critically importance for science and emerging technologies. A fundamentally different approach to electronic structure theory based on quantum fluctuations, proposed by Furche promises to overcome many of these limitations. The methods developed in this project are made available to the public through the Turbomole quantum chemistry software. The project enhances undergraduate education and workforce readiness through a new concentration in Theoretical and Computational Chemistry at UCI and a high school outreach program aimed at students from disadvantaged backgrounds.Furche and his group are developing new methodology to enable predictive simulations of molecules and condensed matter systems such as small-bandgap or correlated materials and clusters, noncovalently bound nanostructures, or optical properties of transition-metal and rare earth compounds. Despite their critical importance for science and emerging technologies, these systems remain nearly intractable with conventional electronic structure methods, due to insufficient accuracy, computational efficiency, or both. Random phase approximation (RPA) methods developed during previous funding periods are the prototype fluctuation-based electronic structure theory. Guided by the successes and failures of RPA, Furche and his group are laying the groundwork for a systematically improvable hierarchy of electronic structure methods based on fluctuations. As opposed to the conventional approach to electron correlation in chemistry, which is based on interacting electron pairs, triples, etc., the methods proposed here describe correlation in many-electron systems by vacuum fluctuations generated by virtual pairs of electrons and holes traveling forward and backward in time (and multiples thereof). Furche and his group also explore a Brueckner functional framework as alternative to Kohn-Sham reference states, and aim to extend the scope of RPA methods to ionization, time-dependent properties, and excited states. Applications include low-valent rare-earth and actinide compounds, and halogen-pi interaction mediated drug design.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.