Accelerating the Prediction of Superconducting Hydrides Using Data-Derived Potentials

A key challenge in materials discovery is to find a viable high temperature superconductor. Hydrogen and hydride materials have long been considered promising materials displaying conventional phonon-mediated superconductivity. [1,2] First-principles crystal structure prediction has been used extensively to predict several superconducting hydrides, of which only a few have been synthesized. 

I will show how machine-learning potentials can be used to circumvent some of the limitations presented by density functional materials. In particular, I will demonstrate how Ephemeral Data-Derived Potentials (EDDPs) [3] can be used to accelerate the prediction of hydrides and to further understand synthesis routes to access metastable states.

The approach is easy to automate and has been applied to a wide range of hydride materials across the periodic table, predicting several previously unknown stable structure types with large unit cells, unusual stoichiometries and novel chemical motifs. We have also used these potentials to better understand the stability our recently predicted ambient-pressure high-temperature Mg-Ir-H superconductor. [4] 

The use machine-learning potentials for multi-species crystal structure prediction presents a new avenue to explore and revisit known phase diagrams. 

[1] Zurek, Eva. ‘Hydrides of the Alkali Metals and Alkaline Earth Metals Under Pressure’. Comments on Inorganic Chemistry 37, no. 2 (4 March 2017): 78–98. https://doi.org/10.1080/02603594.2016.1196679. 

[2] Song, Hao, Zihan Zhang, Tian Cui, Chris J. Pickard, Vladimir Z. Kresin, and Defang Duan. ‘High Tc Superconductivity in Heavy Rare Earth Hydrides’. Chinese Physics Letters 38, no. 10 (1 October 2021): 107401. https://doi.org/10.1088/0256-307X/38/10/107401. 

[3] Pickard, Chris J. ‘Ephemeral Data Derived Potentials for Random Structure Search’. Physical Review B 106, no. 1 (7 July 2022): 014102. https://doi.org/10.1103/PhysRevB.106.014102.

[4] K. Dolui, L. J. Conway, C. Heil, T. A. Strobel, R. Prasankumar, and C. J. Pickard, ‘Feasible route to high-temperature ambient-pressure hydride superconductivity’. arXiv, Oct. 11, 2023. Accessed: Oct. 18, 2023. [Online]. Available: http://arxiv.org/abs/2310.07562