Towards Ab Initio Prediction of Superconducting Properties

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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.