Density Functional Theory of Electronic Structure

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)提供资金的。技术总结该奖项支持理论研究和教育，部分原因是希望提高在凝聚态物理和量子化学中实践的密度泛函理论的准确性。PI描述了交换关联泛函的“阶梯”近似，其中第一级是局部自旋密度近似，第二级是广义梯度近似(GGA)。这些标准近似不能使电子结构计算具有化学上的准确性。特别是，它们不能准确地描述强关联或强空间不均匀密度、长链分子的极化率或高激发态。PI建议通过几个项目的工作来解决这些问题，包括改进(第三级)Meta-GGA方法，改进(第四级)超GGA方法，以及将(第五级)Singwi-Tosi-Land-Sjoelander函数推广到自旋极化的情况。这项研究涉及研究生和本科生的教育以及博士后研究员的专业发展。非技术总结该奖项支持理论研究和教育，长期目标是提高密度泛函理论计算材料电子性质的化学准确性。Kohn和Sham的密度泛函理论是凝聚态物理和量子化学中应用最广泛的电子结构计算方法。要计算原子、分子、生物分子、固体、表面或纳米结构的核骨架、基态能量和电子自旋密度，只需求解自洽的量子力学单电子方程。如果交换相关能作为电子密度的泛函已知，则结果将是精确的。由于没有确切的交换相关能量泛函，人们发展了许多不同的近似泛函，PI在这方面已经成为国际公认的领导者。根据函数表达式的复杂性，不同的近似泛函通常被分成几个主要类别。这些类别被PI表示为交换关联能量的近似阶梯，在交换关联能量上，更高的梯级更复杂和更准确，随着更高梯级的发展可能导致新材料、化学品、药品、设备和工艺的更可靠的计算机设计。目前的奖项支持高级功能的开发，直到第五级，包括广泛使用的功能中没有的化学效应。这项研究涉及研究生和本科生的教育以及博士后的专业发展。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). TECHNICAL SUMMARYThis award supports theoretical research and education motivated in part by the desire to improve the accuracy of density functional theory as practiced in condensed matter physics and quantum chemistry. The PI describes a "ladder" of approximations for the exchange-correlation functional in which the first rung is the local spin density approximation and the second rung is the generalized gradient approximation (GGA). These standard approximations do not enable electronic structure calculations with chemical accuracy. In particular, they do not accurately describe strongly correlated or strongly spatially inhomogeneous densities, polarizabilities of long-chain molecules, or highly excited states. The PI proposes to address these problems through work on several projects, including improvements to (third rung) meta-GGA methods, refinement of (fourth rung) hyper-GGA methods, and generalization of the (fifth rung) Singwi-Tosi-Land-Sjoelander function to the spin-polarized case. This research involves the education of graduate and undergraduate students and the professional development of postdoctoral fellows.NONTECHNICAL SUMMARYThis award supports theoretical research and education with a long-range goal of improving the chemical accuracy of how density functional theory calculates the electronic properties of materials. The density functional theory of Kohn and Sham is the most widely-used method of electronic structure calculation in both condensed matter physics and quantum chemistry. To calculate the nuclear framework, ground state energy, and electron spin densities of an atom, molecule, bio-molecule, solid, surface, or nanostructure, it is only necessary to solve self-consistent quantum mechanical one-electron equations. The results would be exact if the exchange-correlation energy as a functional of the electron density were known exactly. Because no exact exchange-correlation energy functional is known, many different approximate functionals have been developed, and the PI has been an internationally recognized leader in this effort. The different approximate functionals are typically grouped into several major categories depending on the complexity of the functional express. These categories have been denoted by the PI as a ladder of approximations to the exchange-correlation energy, on which higher rungs are more complex and more accurate, with the development of higher rungs potentially leading to the more reliable computer design of new materials, chemicals, pharmaceuticals, devices, and processes. The current award supports the development of advanced functionals up through the fifth rung, including chemical effects not present in widely available functionals. This research involves the education of graduate and undergraduate students and the professional development of postdoctoral fellows.