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）资助的。该奖项支持理论研究和教育，部分原因是希望提高密度泛函理论在凝聚态物理和量子化学中的准确性。PI描述了交换相关泛函近似的“阶梯”，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精度。特别是，它们不能准确地描述强相关或强空间非均匀密度、长链分子的极化性或高激发态。PI建议通过几个项目来解决这些问题，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情况。本研究涉及研究生和本科生的教育以及博士后的专业发展。该奖项支持理论研究和教育，其长期目标是提高密度泛函理论计算材料电子特性的化学准确性。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。为了计算原子、分子、生物分子、固体、表面或纳米结构的核框架、基态能量和电子自旋密度，只需要求解自洽量子力学单电子方程。如果确切地知道交换相关能作为电子密度的函数，结果将是准确的。由于没有确切的交换相关能量泛函是已知的，许多不同的近似泛函已经开发出来，PI已经在这方面的努力国际公认的领导者。根据函数表达式的复杂程度，不同的近似函数通常分为几大类。这些类别被PI表示为交换相关能的近似阶梯，其中越高的阶梯越复杂，越准确，随着越高的阶梯的发展，新材料、化学品、药品、设备和工艺的计算机设计可能会更可靠。目前的奖项支持开发先进的功能到第五梯级，包括在广泛可用的功能中不存在的化学效应。本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.