Density Functional Theory of Molecular Fragments: Strong Electron Correlation Beyond Density Functional Approximations

在化学系化学理论，模型和计算方法课程的支持下，普渡大学的Adam Wasserman教授正在开发先进的理论和方法，用于分子和材料电子结构的计算机模拟，具有新的能力，能够高度准确地预测这些系统的性能和实验解释。此外，分子碎片密度泛函理论的新方法旨在为日益复杂的系统提供计算效率。Wasserman博士和他的研究小组将专注于提高这些方法的准确性和效率，以应对具有挑战性的“强相关型”系统。这些系统中，电子相关效应占主导地位，通常是遥不可及的标准近似的基础上Kohn-Sham密度泛函理论，最广泛使用的电子结构方法。除了拟议的研究工作产生的更广泛的影响，PI在普渡大学学生的拉丁美洲社区的领导将继续下去。其他教育活动包括由PI共同举办的两年一度的含时密度泛函理论学校和研讨会，以及PI将继续举办的关于"科学与社会进步"的海外学习课程。在这个奖项下，Wasserman研究小组将专注于两个主要方向：（1）提高密度泛函理论（DFT）计算的准确性，用于超出最先进的密度泛函近似所能达到的系统;（2）提高计算效率。这种分离是可能的，最近的密度到潜在的反演技术的发展，允许计算数值精确的非添加剂非相互作用的动能。为了实现第一个目标，Wasserman和他的团队将采用片段密度的重叠泛函来构建和测试片段间交换相关能量泛函的物理近似。为了实现第二个，一个双管齐下的方法将遵循其中（a）半本地碎片密度泛函将开发基于精确的约束的非添加剂动能泛函;和（B）一个训练有素的神经网络将被用来将非本地的影响到一个元广义梯度近似（GGA）功能的完整的非相互作用的动能泛函。所有的进展都将通过用于密度嵌入计算的开源代码提供给更广泛的科学界。该奖项反映了NSF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。

With support from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry, Professor Adam Wasserman of Purdue University is developing advanced theories and methods for computer simulation of the electronic structure of molecules and materials with new capabilities to enable highly accurate prediction of properties and interpretation of experiment for these systems. In addition, the new method of density functional theory of molecular fragments aims to provide computational efficiency for systems of ever-increasing complexity. Dr. Wasserman and his research group will focus on improving both the accuracy and the efficiency of these methods for the challenging systems of the “strongly-correlated type.” These systems in which electron correlation effects dominate, are typically out of reach for standard approximations based on Kohn-Sham Density Functional Theory, the most widely used electronic structure method. In addition to the broader impact resulting from the proposed research efforts, the PI's leadership within the Latin-American community of Purdue students will continue. Other educational activities include a bi-annual School and Workshop on Time-dependent DFT co-organized by the PI and a study-abroad course on “Science and social progress” that the PI will continue organizing.Under this award, the Wasserman research group will focus on two major thrusts: (1) Improving the accuracy of density-functional theory (DFT) calculations for systems that lie beyond the reach of state-of-the-art density-functional approximations; and (2) Improving the efficiency of such calculations. This separation is made possible by the development of recent density-to-potential inversion techniques that allow for the calculation of numerically exact non-additive noninteracting kinetic energies. To achieve the first goal, Wasserman and his group will employ an overlap functional of the fragment densities to construct and test physically motivated approximations for the inter-fragment exchange-correlation energy functional. To achieve the second, a two-pronged approach will be followed in which (a) a semi-local fragment-density functional will be developed based on exact constraints for the non-additive kinetic-energy functional; and (b) a trained neural network will be used to incorporate non-local effects into a meta-generalized gradient approximation (GGA) functional for the full noninteracting kinetic energy functional. All advances will be made available to the broader scientific community through open-source codes for density embedding calculations.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.