CAREER: Efficient DFT-based computational approach for correlated systems

该职业奖支持理论和计算研究以及教育，以开发、验证和传播新的基于密度功能理论的第一性原理计算方法，该方法将能够以比现有的基于密度功能理论的计算更高的精度描述相关和弱相关材料。这一目标将通过对选择性作用于“相关”电子态的近似总能量的修正来实现。新的校正功能将被设计用来捕捉特定的多体属性。该泛函将在二次量化模型哈密顿量上形成，该模型已被制定并广泛用于研究相关电子的行为。修正将被纳入密度泛函理论能量泛函，并将包括从第一原理计算的有效相互作用。已经在使用标准密度泛函理论方法的计算方法的扩展将进一步扩展新的计算工具的描述能力。该项目预计将沿着以下步骤进行：1)制定一个广义泛函，该泛函对被占领和半被占领状态的作用不同。这种推广将用于研究最优的细化，以提高灵活性和泛函的一般适用性。2)定义了一种有效电子耦合从相互作用核出发的运行时计算的高效、精确的计算方法。3)建立了一种通用的修正哈密顿函数，能够在控制的近似范围内，将选定的多体电子能量项重新引入近似的交换相关泛函中。新的校正功能旨在大大提高电子结构计算的精度和数值效率，从而实现技术应用中材料的筛选和优化。特别感兴趣的是预测太阳能电池的新材料，烷烃的催化转化，功能金属合金和氧化物，高温超导体的母体化合物，先进电子产品的氧化物和光催化。该奖项还支持教育活动，旨在为不熟悉计算技术的学生和高级科学家提供第一原理电子结构计算。具体目标包括：开发一门关于如何进行可靠的密度泛函理论计算的课程，供在实验组工作的研究生使用，以及开发动手计算课程并将其整合到其他课程中。PI将继续参加由第一原理电子结构代码Quantum-ESPRESSO的开发者组织的暑期学校和教程。该职业奖支持理论和计算研究，以及开发计算技术的教育，以有效和准确地模拟含有相互作用特别强烈的电子的材料。这些相关材料的著名例子是过渡金属和稀土化合物，它们通常包含电子，这些电子非常局限于过渡金属或稀土原子周围。这些电子在确定强相关材料的基本性质方面起着重要作用。相关材料可能出现在广泛的技术应用中，包括：高温超导体，太阳能电池，催化剂，能量转换和存储系统，以及新兴的电子设备技术，除了电荷，利用电子的磁性来操作。相关材料的精确计算建模是一个基本的挑战；通过精确表征控制其行为的微观因素，以及有效利用计算机筛选许多候选材料以预测最适合特定应用的材料，这种能力将极大地促进具有所需性能的材料的设计和优化。大多数可用于材料特定计算的预测计算方法要么计算成本很高，要么不够精确，无法捕捉具有强相互作用电子的材料的物理性质。该奖项支持开发和实施新技术，以准确有效地预测相关材料的性质。该奖项还支持教育活动，教不熟悉计算技术的学生和高级科学家如何有效地使用先进的计算材料建模工具。具体目标包括：开发一门关于如何执行可靠的预测材料建模计算的课程，特别关注在实验组工作的研究生，以及开发“动手”计算课程，将其整合到其他课程中。PI将继续参加由第一原理电子结构代码Quantum-ESPRESSO的开发人员组织的暑期学校和教程。

TECHNICAL SUMMARYThis CAREER award supports theoretical and computational research, and education to develop, validate, and disseminate a new first-principles density-functional-theory-based computational approach that will be able to describe correlated and weakly correlated materials at a higher level of accuracy than existing density-functional-theory-based calculations. This objective will be pursued through a correction to the approximate total energy that selectively acts on 'correlated' electronic states. The new correction functional will be designed to capture specific many-body properties. This functional will be shaped on second-quantization model Hamiltonians that have been formulated and broadly used to study the behavior of correlated electrons. The correction will be incorporated into the density-functional-theory energy functional and will include effective interactions computed from first principles. The extension of computational methods already in use with standard density-functional-theory methods will further expand the descriptive power of the new computational tool. This project is envisioned to proceed along the following steps:1) Formulation of a generalized functional that acts differently on occupied and semi-occupied states. This generalization will be used to study optimal refinements to improve the flexibility and the general applicability of the functional.2) Definition of an efficient and accurate computational method for the run-time calculation of effective electronic couplings from the interaction kernel.3) Development of a general corrective Hamiltonian able to reintroduce, within controlled approximations, selected many-body terms of the electronic energy into approximate exchange-correlation functionals. The new corrective functional is aimed to greatly improve the accuracy and the numerical efficiency of electronic structure calculations enabling the screening and optimization of materials for technological applications. Of particular interest is predicting novel materials for solar cells, catalytic conversion of alkanes, functional metallic alloys and oxides, parent compounds of high temperature superconductors, oxides for advanced electronics, and photo-catalysis.This award also supports educational activities with the aim of making first-principles electronic-structure calculations accessible to students and senior scientists who are not familiar with computational techniques. Specific objectives include: developing a course on how to perform reliable density functional theory calculations accessible to graduate students who work in experimental groups, and developing hands-on computational sessions and integrating them into other courses. The PI will continue to participate in summer schools and tutorials organized by the developers of the first-principles electronic-structure code Quantum-ESPRESSO. NON TECHNICAL SUMMARYThis CAREER award supports theoretical and computational research, and education to develop computational techniques for efficient and accurate modeling of materials that contain electrons that interact with each other particularly strongly. Notable examples of these correlated materials are transition-metal and rare-earth compounds that usually contain electrons that are very localized around a transition metal or rare earth atom. These electrons play an important role in determining essential properties of strongly correlated materials. Correlated materials may appear in a broad spectrum of technological applications that includes: high temperature superconductors, solar cells, catalysts, energy conversion and storage systems, and emerging electronic device technologies that, in addition to charge, exploit magnetic properties of the electron for their operation. Accurate computational modeling of correlated materials is a fundamental challenge; the capability would greatly facilitate the design and optimization of materials with desired properties through both the precise characterization of the microscopic factors controlling their behavior, and the efficient use of computers to screen many candidate materials to predict materials which will be optimally suited for a particular application. Most available predictive computational approaches to perform materials specific calculations are either very computationally expensive or not accurate enough to capture the physical properties of materials with strongly interacting electrons. This award supports developing and implementing new techniques to predict accurately and efficiently the properties of correlated materials. This award also supports educational activities to teach students and senior scientists who are not familiar with computational techniques how to use effectively advanced computational materials modeling tools. Specific objectives include: developing a course on how to perform reliable predictive materials modeling calculations, focusing particularly on graduate students who work in experimental groups, and developing 'hands-on' computational sessions integrating them into other courses. The PI will continue to participate in summer schools and tutorials organized by the developers of the first principles electronic structure code Quantum-ESPRESSO.