A United Theory of van der Waals forces in Non-Local Density Functional Theory

材料研究部和高级网络基础设施办公室为该奖项提供资金，支持研究和教育，以开发材料计算建模的方法。我们的社会在生活的许多方面都依赖于新材料，从智能手机和计算机到运输和工业流程。从历史上看，这种材料是在实验室中开发的，但这种方法非常昂贵和耗时。随着计算机技术的进步，我们现在可以在实验室中制造材料之前对材料的特性进行建模，这为开发新材料提供了一种潜在的更便宜和更快的方法。所有材料都是通过其组成原子和/或分子之间的基本力结合在一起的。虽然比大多数其他力弱，但货车德瓦尔斯力对许多化学/生物/工业过程和日常生活中的现象至关重要，例如允许壁虎爬墙。不幸的是，最广泛使用的材料建模计算技术难以捕捉货车范德华力。随着时间的推移，已经开发出两种不同的方法，代表不同的设计理念。有了这个NSF奖，PI寻求将两者联合收割机结合起来，目的是得到一个改进的统一理论，结合了两种近似的优点，克服了它们的缺点。该奖项的主要科学成果将是一个免费提供的计算机代码，使研究人员能够更准确地模拟货车德瓦尔斯力发挥重要作用的材料。对于该项目的教育部分，年轻科学家将接受培训和指导，成为对我们国家持续成功至关重要的领域的独立研究人员。此外，研究活动与当地科学博物馆的外联活动相结合，以提高科学素养和社区对科学的参与。拟议中的当地科学博物馆分子游乐场每年将接待20多万游客，扩大居住在皮埃蒙特的人对科学的参与，北卡罗来纳州的三合会地区。技术总结材料研究部和高级网络基础设施办公室为该奖项提供资金，支持研究和教育，以发展非局部密度内的货车范德华力的统一理论功能理论我们的社会对新材料的需求不断增加，这使得他们的开发战略转向在实验室合成之前在计算机上模拟材料的特性。因此，现代方法准确模拟新型材料中各种相互作用的能力成为焦点。特别令人感兴趣的是货车范德华相互作用，这是至关重要的许多材料的结构，从水泥到DNA，在催化，气体封存/储存和生物化学过程中发挥着复杂的作用。由于其有利的计算成本，密度泛函理论（DFT）是从头计算建模方法的选择。然而，不幸的是，用标准近似法不能可靠地捕捉到货车德瓦尔斯相互作用。两个基于密度的近似交换相关泛函已被开发，将货车德瓦尔斯相互作用的DFT，两者的优点和缺点。目前的建议的目的是得到一个改进的和统一的理论，结合这两个近似的优点，克服它们的缺点。结果将是一个组合的，无参数的，普遍适用的和实用的方法来捕捉货车德瓦尔斯相互作用的DFT与改进的accuracy.While这两个近似有一个共同的出发点在多体理论，他们在非局部相关密度泛函的建设不同。在这两种情况下，材料的介电函数都是通过简单的等离子体极点模型来近似的，但是具体的模型坚持不同数量的精确物理约束，从而导致不同复杂性的模型。令人惊讶的是，具有较少精确约束的更简单的方法通常在准确性方面表现更好，但在不同情况下存在可转移性问题。拟议的工作提出了一种途径，以统一这两种方法，并找到一个更好的描述等离子体磁极模型，坚持更重要的约束，如电荷守恒，但也很容易评估。该奖项的主要成果将是一个计算工具，以更准确地捕捉DFT内的非本地货车德瓦尔斯效应。PI计划将开发的软件作为开源软件发布，作为公共领域电子结构包Quantum-Espresso的一部分，并通过确保感兴趣的研究人员能够为代码库做出贡献，围绕该语言建立一个用户社区。这将使该项目得到更广泛的发展。高级网络基础设施办公室（Office of Advanced Cyberinfrastructure）的软件集群对此特别感兴趣，该办公室为该奖项提供了共同资助。在该项目的教育部分，年轻科学家将接受培训和指导，成为对我们国家持续成功至关重要的领域的独立研究人员。此外，研究活动与当地科学博物馆的外联活动相结合，以提高科学素养和社区对科学的参与。拟议中的当地科学博物馆的分子游乐场每年将接待20多万游客，扩大居住在北卡罗来纳州皮埃蒙特-三合会地区的人对科学的参与。

NONTECHNICAL SUMMARYThe Division of Materials Research and the Office of Advanced Cyberinfrastructure contribute funds to this award that supports research and education towards developing methodologies for the computational modeling of materials. Our society depends on novel materials for many aspects of life, ranging from smart phones and computers to transportation and industrial processes. Historically, such materials have been developed in experimental labs, but that approach is very expensive and time consuming. With advances in computer technology, we are now at a point where we can model the properties of materials before they are ever made in a lab, providing a potentially less expensive and faster way to develop new materials.All materials are held together by fundamental forces between their constituent atoms and/or molecules. Although weaker than most other forces, the van der Waals force is crucial for many chemical/biological/industrial processes and phenomena of every-day life, allowing for example a gecko to run up a wall. Unfortunately, the most widely used computational technique for modeling materials has difficulty capturing van der Waals forces. Over time, two distinct approaches have been developed that represent different design philosophies. With this NSF award, the PI seeks to combine both, with the objective to derive an improved and unified theory that combines the advantages of both approximations and overcomes their shortcomings. The main scientific outcome of the award will be a freely available computer code that allows researchers to more accurately model materials where van der Waals forces play an important role.For the educational part of this project, young scientists will be trained and mentored to become independent researchers in fields that are important to our nation's continued success. In addition, the research activities are coupled with outreach at a local science museum to increase scientific literacy and engagement with science in the community. The proposed Molecular Playground at the local science museum will serve over 200,000 visitors annually, broadening participation in science among those who live in the Piedmont-Triad area in North Carolina.TECHNICAL SUMMARYThe Division of Materials Research and the Office of Advanced Cyberinfrastructure contribute funds to this award that supports research and education towards developing a unified theory of van der Waals forces within nonlocal density functional theory. Our society's increased need for novel materials has shifted their development strategy to modeling a material's properties on the computer before it is ever synthesized in the lab. The capability of modern methods to accurately model a variety of interactions in novel materials has thus come into focus. Of particular interest are van der Waals interactions, which are crucial for the structure of many materials reaching from cement to DNA, playing intricate roles in catalysis, gas sequestration/storage, and biochemical processes. Due to its favorable computational cost, density functional theory (DFT) is the ab initio modeling method of choice. However, with standard approximations it unfortunately cannot reliably capture van der Waals interactions. Two density-based approximations to the exchange-correlation functional have been developed that incorporate van der Waals interactions in DFT, both with advantages and shortcomings. The objective of the current proposal is to derive an improved and unified theory that combines the advantages of both approximations and overcomes their shortcomings. The result will be a combined, parameter-free, and generally applicable and practical method to capture van der Waals interactions in DFT with improved accuracy.While both approximations have a common starting point in many-body theory, they differ in the construction of their nonlocal correlation density functional. In both cases, the dielectric function of the material is approximated through a simple plasmon-pole model, but the specific models adhere to different numbers of exact physical constraints and thus result in models of different complexity. Surprisingly, the simpler method with fewer exact constraints often performs better in terms of accuracy, but suffers from problems of transferability to materials in different situations. The proposed work presents a pathway to unify both methods and find an improved description of the plasmon-pole model that adheres to the more important constraints, such as charge conservation, but is also simple to evaluate. The main outcome of the award will be a computational tool to more accurately capture nonlocal van der Waals effects within DFT. The PI plans to release the developed software as open source, as part of the public-domain electronic-structure package Quantum-Espresso, and build a user community around the language by ensuring that interested researchers are able to contribute to the codebase. This will allow a wider growth of the  project. This aspect is of special interest to the software cluster in the Office of Advanced Cyberinfrastructure, which has provided co-funding for this award.For the educational part of this project, young scientists will be trained and mentored to become independent researchers in fields that are important to our nation's continued success. In addition, the research activities are coupled with outreach at a local science museum to increase scientific literacy and engagement with science in the community. The proposed Molecular Playground at the local science museum will serve over 200,000 visitors annually, broadening participation in science among those who live in the Piedmont-Triad area in North Carolina.