In Search of an Optimum Reference

在化学系化学理论、模型和计算方法计划的支持下，加州大学欧文分校(UCI)的Filipp Furche致力于开发、实施、评估和应用计算化学的一系列新的电子结构方法，以解决当前理论的关键局限性。这些限制阻碍了我们在催化、药物设计、大气化学和量子材料等领域准确预测和模拟能量和性质的能力。Furche提出的“最佳参考”(OR)方法承诺通过设计使当前方法的“参考偏差”最小化，并有望将电子结构计算的范围扩展到迄今难以捉摸的体系和性质。在这个项目中开发的方法将通过透波莫尔量子化学软件向公众开放。该计划将通过UCI的量子科学跨学科计划和针对否则参与研究机会有限的学生的高中推广计划来支持教育和劳动力准备。该项目建立在轨道优化和Brueckner方法以及自洽随机相位近似方法等先前发展的基础上，并旨在推广这些发展。虽然量子化学中越来越复杂的关联处理方法的发展为“行为良好”的系统产生了极其准确的方法，但今天使用的几乎所有电子关联方法的致命弱点是它们对参考态的非物理依赖，即对感兴趣的物理量子态的定性准确且易于计算的近似。Furche的工作旨在开发稳定的OR方法，并以四个命题为指导：(I)OR应该在定义明确的度量中最小化到感兴趣的物理状态的距离，(Ii)具有明确的物理意义并产生模型化学，(Iii)总能量在OR应该是固定的，(Iv)作为参考的泛函的关联能量必须服从显式的、可控的近似。由此产生的方法将被评估其捕获开壳d元素和f元素化合物系统的磁性和自旋性质的能力，这对现有方法特别具有挑战性。这一奖项反映了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。

With support from the Chemical Theory, Models and Computational Methods Program in the Division of Chemistry, Filipp Furche of the University of California, Irvine (UCI) aims to develop, implement, evaluate, and apply a new family of electronic structure methods of computational chemistry to address critical limitations of current theories. These limitations hamper our ability to predict and simulate accurately energies and properties in areas such as catalysis, drug design, atmospheric chemistry, and quantum materials. The ‘optimum reference’ (OR) methods proposed by Furche promise to minimize by design the ‘reference bias’ of current methods and are expected to extend the scope of electronic structure calculations to hitherto elusive systems and properties. The methods developed in this project will be made available to the public through the Turbomole quantum chemistry software. The program will support education and workforce readiness through an interdisciplinary program in quantum science at UCI and a high school outreach program aimed at students who otherwise would have limited opportunities to participate in research.This project builds on and aims to generalize previous developments such as orbital optimization and Brueckner methods, as well as self-consistent random phase approximation methods. While the development of ever more sophisticated correlation treatments in quantum chemistry has produced exceedingly accurate methods for "well behaved" systems, the Achilles' heel of virtually all electron correlation methods in use today is their unphysical dependence on a reference state, i.e., a qualitatively accurate, and readily computable approximation to the physical quantum state of interest. Furche's work aims to develop stable OR methods guided by four propositions: (i) The OR should minimize the distance to the physical state of interest in a well-defined metric, (ii) have a well-defined physical meaning and give rise to a model chemistry, (iii) the total energy should be stationary at the OR, (iv) the correlation energy as a functional of the reference must be amenable to explicit, controlled approximations. The resulting methods will be assessed for their ability to capture magnetic and spin properties of open-shell d- and f-element compounds systems that are particularly challenging for available approaches.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.