Density Functional Theory of Molecular Fragments

普渡大学的Adam Wasserman教授获得了化学系化学理论、模型和计算方法项目的奖励，以提高基于密度泛函理论（DFT）的分子系统性质的电子结构计算的准确性和效率。沃瑟曼博士和他的研究小组正在开发一种新的分子片段密度泛函理论，这些分子片段是大分子的一部分。他们正在研究如何通过化学键断裂或形成时发生的电子密度扭曲来计算分子和材料的电子特性。这一点很重要，有几个原因：首先，对碎片的关注使得在并行超级计算机上进行大规模计算成为可能，从而允许进行目前计算机技术无法实现的研究。其次，对碎片的关注允许新方法优于DFT中常用的现代近似，特别是对于所谓的强电子相关性主导的系统。第三，当化学键被拉伸时，对碎片的关注允许对系统进行精确的计算机模拟。这些系统普遍存在于催化过程中重要的分子中间物种中，其研究超出了当今DFT的范围。除了培训本科生和研究生以及为科学界开发开源代码之外，Wasserman博士还组织专门的专题讨论会并开发跨文化项目，以增加西班牙裔人对科学研究的参与。Wasserman博士和他的研究小组在不放弃DFT核心原理的情况下，采用了一种新的DFT视角，从而提高了涉及化学键拉伸和断裂的密度嵌入计算的准确性。这是通过两个方面来完成的：(1)对交换相关能量泛函的非加性部分的物理动机近似的发展；(2)通过对非相互作用动能泛函的非加性部分的新逼近，改进了半局部Kohn-Sham DFT。这项工作涉及开放量子系统的多体理论的应用，以及在广泛可用的量子化学软件包中的实现。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。

Professor Adam Wasserman of Purdue University is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry to improve the accuracy and efficiency of electronic structure calculations of properties of molecular systems based on density functional theory (DFT). Dr. Wasserman and his research group are developing a novel density functional theory of molecular fragments, which are parts of larger molecules. They are investigating how the electronic properties of molecules and materials can be calculated from the electron density distortions that occur when chemical bonds are broken or formed. This is important for several reasons: First, the focus on fragments leads to the possibility of carrying out large-scale calculations on parallel supercomputers, allowing for studies that would not be feasible otherwise with present-day computer technology. Second, the focus on fragments allows for new methods that outperform commonly used modern approximations in DFT, especially for systems dominated by so-called strong electron correlations. Third, the focus on fragments allows for accurate computer simulations of systems when chemical bonds are stretched. These systems are ubiquitous in molecular intermediate species of importance to catalytic processes, whose study is beyond the reach of present-day DFT. In addition to training undergraduate and graduate students and developing open-source codes for the scientific community, Dr. Wasserman organizes specialized symposia and develops inter-cultural projects that increase Hispanic participation in scientific research.By adopting a new perspective on DFT without abandoning its core principles, Dr. Wasserman and his research group are improving the accuracy of density-embedding calculations that involve the stretching and breaking of chemical bonds. This is being done via two fronts: (1) The development of physically-motivated approximations to the non-additive pieces of the exchange-correlation energy functional; and (2) The improvement of semi-local Kohn-Sham DFT through new approximations to the non-additive piece of the non-interacting kinetic-energy functional. The work involves applications of the many-body theory of open quantum systems and implementations into broadly available quantum-chemistry software packages.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.