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DFT Accurate Interatomic Potential for Molten NaCl from Machine Learning

preprint
submitted on 21.05.2020 and posted on 22.05.2020 by Samuel Tovey, Anand Narayanan Krishnamoorthy, ganesh sivaraman, Jicheng Guo, Chris Benmore, Andreas Heuer, Christian Holm

Molten alkali chloride salts are a critical component in concentrated solar power and nuclear applications. Despite their ubiquity, the extreme chemical reactivity of molten alkali chlorides at high temperatures has presented a significant challenge in characterizing atomic structures and dynamic properties experimentally. Here we investigate

molten NaCl by performing high temperature molecular dynamics simulations using a Gaussian Approximation Potential (GAP) trained on Density Functional Theory (DFT) datasets. Our GAP model, trained with a meager 1000 atomic configurations, arrives at near DFT accuracy with a mean absolute error of 1.5 meV/atom, thus enabling fast analysis of high temperature salt properties on large length (5000 ion pairs) and time (> 1ns) scales, currently inaccessible to ab initio simulations. Calculated structure factors and diffusion constants from our GAP model simulations show excellent agreement with experiments. Our results indicate that GAP models are able to capture the many-body interactions required to accurately model ionic-systems.

Funding

This material is based upon work supported by Laboratory Directed Research and Development (LDRD-2020-0226) funding from Argonne National Laboratory, provided by the Director, O?ffice of Science, of the U.S. Department of Energy under Contract No. DE-AC02- 06CH11357.

This research used resources of the Argonne Leadership Computing Facility, which is a DOE O?ffice of Science User Facility supported under Contract DE-AC02- 06CH11357. Argonne National Laboratory's work was supported by the U.S. Department of Energy, O?ffice of Science, under contract DE-AC02-06CH11357.

CJB was supported by the U.S. DOE under Contract DE-ACO2-06CH11357.

S.T gratefully acknowledges ?financial support from the International Max Planck Research School (IMPRS) as well as the Max Planck Institute for Condensed Matter Physics.

C.H and A.N.K acknowledge ?nancial support from the German Funding Agency (DeutscheForschungsgemeinschaft-DFG) under Germanys Excellence Stratergy - EXC 2075-390740016.

History

Email Address of Submitting Author

gsivaraman@anl.gov

Institution

ARGONNE NATIONAL LABORATORY

Country

USA

ORCID For Submitting Author

0000-0001-9056-9855

Declaration of Conflict of Interest

There are no conflicts to declare.

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