Development and Applications of Density Functional Methods for Large Systems

在化学系化学理论，模型和计算方法（CTMC）计划的支持下，杜克大学的杨伟涛教授将开发密度泛函理论方法，用于准确预测大型复杂系统的能量，电荷分布和光谱。 所提出的发展应该在生物学、化学、物理学、工程学和纳米科学与技术的广泛计算建模中具有广泛的应用。杨和他的研究小组将通过出版原始研究成果和公开分发软件包来传播这些研究所获得的知识和技术。 拟议的工作将有助于开发人力资源，为未来一代的理论和计算化学研究人员，并将扩大参与科学，技术，工程和数学通过项目种子。根据该奖项，Weitao Yang和他的研究小组将开发对常见密度泛函近似的修正，以满足分数电荷和分数自旋的关键约束。常用的近似泛函有主要的系统误差：离域误差，作为偏离精确的线性条件的分数电荷在一个凸的行为，和强/静态相关误差，作为违反恒定条件的分数自旋。克服这些错误的必要条件已表示在分数电荷，分数自旋及其组合。 密度泛函理论中的突出挑战仍然是满足这些条件并克服相关的系统误差。Yang和他的团队将专注于以下三个方向：（1）用定域轨道标度校正消除离域误差，（2）探索从基态密度泛函理论计算获得激发态能量信息的基本原理，（3）用定域轨道标度校正和基于线性响应理论的多参考密度泛函理论减少静态校正误差。这项工作的广泛的科学影响将得到加强，因为杨团队计划将这项工作中开发的计算软件免费提供给科学界。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

With support from the Chemical Theory, Models and Computational Methods (CTMC) program in the Division of Chemistry, Professor Weitao Yang of Duke University will develop methods in density functional theory for accurate prediction of energy, charge distributions and optical spectroscopy for large and complex systems. The proposed developments should have broad application in a wide range of computational modeling in biology, chemistry, physics, engineering and nano- science and technology. Yang and his research group will disseminate the knowledge and technology gained through these studies through publication of original research work and the public distribution of software packages. The proposed work will contribute to the development of human resources, for the future generation of theoretical and computational chemistry researchers, and will broaden participation in science, technology, engineering and mathematics through Project SEED. Under this award, Weitao Yang and his research group will develop corrections to common density functional approximations to satisfy key constraints on fractional charges and fractional spins. Commonly used approximate functionals have major systematic errors: the delocalization error, as the deviation from the exact linearity condition for fractional charges in a convex behavior, and the strong/static correlation error, as the violation of the constancy condition for fractional spins. Necessary conditions for overcoming these errors have been expressed in terms of fractional charges, fractional spins and their combination. Outstanding challenges in density functional theory remain to satisfy these conditions and overcome the associated systematic errors. Yang and his group will focus on the following three directions: (1) eliminating delocalization error with localized orbital scaling correction, (2) exploring the fundamental principles of obtaining excited state energetic information from ground state density functional theory calculations, and (3) reducing static correction error with localized orbital scaling correction and with multireference density functional theory based on the linear response theory. The broad scientific impact of the work will be enhanced as the Yang team plans to make the computational software developed in this work freely available to the scientific community.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.