Towards Ab Initio Prediction of Superconducting Properties

该奖项支持研究、计算和教育，旨在开发和采用先进的计算方法在原子尺度上模拟超导材料。超导性，即电流在某一临界温度以下的无电阻流动，是量子力学在日常生活中最壮观的表现之一。这一特性正在技术应用中得到开发，包括能源储存和分配、医药、电子和运输。在这个项目中，新的功能将在电子-声子万尼尔（EPW）代码中实现，这是一个开源软件包，作为广泛使用的量子ESPRESSO平台的组成部分分发。开发的能力将使研究已知超导材料的趋势和通过使用高性能计算识别新的候选超导材料成为可能。这些方法将应用于一类称为过渡金属二硫族化物的二维材料，以提供对这些重要材料超导机制的见解，这些重要材料一直是最近基础和应用驱动研究的主题。该奖项支持在计算材料科学和高性能计算方面的研究生和本科生的培训；这将有助于为推进网络基础设施和计算材料研究发展一支熟练的劳动力队伍。为了帮助吸引新一代科学家进入STEM学科，PI的团队将参加为纽约北部地区小学生组织的外展活动。所有新的计算特性将免费提供给更广泛的物理学家、化学家和材料科学家。该奖项支持研究、计算和教育，目的是应用理论/计算方法来模拟超导体，而无需诉诸可调参数。由于电子-电子相互作用、自旋涨落、等离子体效应、电子-声子顶点校正以及其他通常被忽视或不充分包括的因素，在当今超导特性的理论研究中，实现与实验的定量一致是出了名的困难。在提议的项目中，新的先进功能将被引入到开源的EPW代码中，以实现材料超导特性的预测计算。开发的方法将通过计算块状和二维过渡金属二硫族化合物的超导特性来验证，二硫族化合物是一类具有电荷密度波、超导和拓扑非寻常相的化合物。在tmd中一个重要的未解决的问题是，为什么计算的临界温度和零温度超导间隙与实验值相比往往被系统地高估。开发的工具将在开源的GNU GPL下发布，以达到更广泛的科学家社区。PI将对研究生和本科生进行材料建模和编程方面的培训，并共同组织研讨会，教授EPW代码的基本理论和最佳使用。最后，为了提高中学生对科学的兴趣，PI小组将在宾厄姆顿大学物理推广计划组织的科学展览中进行演示。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。

NONTECHNICAL SUMMARYThis award supports research, computation, and education aimed to develop and employ advanced computational methods for modeling superconducting materials at the atomic scale. Superconductivity, the resistance-free flow of electrical current below a certain critical temperature, is one of the most spectacular manifestations of quantum mechanics on the scale of everyday life. This property is being exploited in technological applications, including energy storage and distribution, medicine, electronics, and transportation.Within this project, new functionalities will be implemented in the electron-phonon Wannier (EPW) code, which is an open-source software package distributed as an integral part of the widely used Quantum ESPRESSO platform. The developed capabilities will enable the investigation of trends in known superconducting materials and the identification of new candidate superconducting materials through the use of high-performance computing. The methods will be applied to a class of two-dimensional materials called transition metal dichalcogenides to provide insights into the mechanism of superconductivity in these important materials which have been the subject of recent fundamental and application-driven research.This award supports training of graduate and undergraduate students in computational materials science and high-performance computing; this will contribute to the development of a skilled workforce for advancing cyberinfrastructure and computational materials research. To help attract a new generation of scientists into the STEM disciplines, the PI’s team will take part in outreach activities organized for elementary school students in the upstate New York area. All new computational features will be made freely available to reach a wider community of physicists, chemists, and materials scientists.TECHNCIAL SUMMARY This award supports research, computation, and education with the aim to apply theoretical/computational methods for modeling superconductors without resorting to adjustable parameters. Achieving quantitative agreement with experiment in present-day theoretical studies of superconducting properties is notoriously difficult because of electron-electron interactions, spin fluctuations, plasmonic effects, electron-phonon vertex corrections, and other factors that are commonly neglected or inadequately included. Within the proposed project, new advanced functionalities will be introduced into the open-source EPW code to enable predictive calculations of superconducting properties of materials. The developed methodology will be validated by performing calculations of the superconducting properties of bulk and two-dimensional transition metal dichalcogenides, a family of compounds that hosts charge density wave, superconducting, and topologically non-trivial phases. An important unresolved question in TMDs is why the calculated critical temperature and zero-temperature superconducting gap tend to be systematically overestimated compared to the experimental values.The developed tools will be released under the open-source GNU GPL to reach a wider community of scientists. The PI will train graduate and undergraduate students in materials modeling and programming, and co-organize workshops to teach the underlying theory and optimal usage of the EPW code. Finally, in order to raise middle school students' interest in science, the PI’s group will give demonstrations as part of the Science Shows organized by the Binghamton University’s Physics Outreach Program.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.