Abstract
Planetary interiors experience high-pressure-high temperature conditions that give rise to unconventional states of matter, reshaping our understanding of planetary dynamics and the generation of magnetic fields. Here, using first-principles computational simulations in combination with machine-learning interatomic potentials, we predict a distinct atomic state, termed a quasi-1D superionic phase, that emerges in a stable carbohydride (CH) compound under giant planetary interior conditions. This phase originates from temperature-induced transformations and features a chiral carbon framework intertwined with dynamic hydrogen helices. At 0 K, electronic redistribution along the hydrogen sublattice induces metallization. In contrast, upon heating, carbon atoms form a rigid lattice, and hydrogen exhibits rotational motion in the xy-plane and diffusion along the z-axis, resulting in anisotropic mobility. A high-pressure-temperature phase diagram reveals sequential transitions from solid to quasi-1D superionic, 3D superionic, and fluid states. The quasi-1D superionic CH phase exhibits pronounced anisotropy in electronic, thermal, and ionic conductivity, with electronic transport predominating and the ionic contribution remaining negligible. This anisotropic behavior provides a microscopic mechanism for directional energy and charge transport under high-pressure and high-temperature conditions, offering insight into how structural anisotropy can govern transport properties in materials subjected to ultra-high pressures. This anisotropic behavior provides a microscopic mechanism for directional energy and charge transport under extreme conditions, offering new insights into the behavior of high-pressure materials and magnetic phenomena in giant and sub-Neptune exoplanets.
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Data availability
The data that support the findings of this study are available on Zenodo77 (https://doi.org/10.5281/zenodo.18484546). Additional supporting data and figures are provided in the Supplementary Information. Structural information in our crystal structure prediction is provided as Supplementary Data 1. We provide DFT-MD and MLP-MD simulation movies in the additional supplementary information (see Description of Additional Supplementary Information). Source data are provided in this paper.
Code availability
MAGUS, LAMMPS, DeepMD and SPR-KKR are free and open-source software packages, available at https://gitlab.com/bigd4/magus, https://lammps.sandia.gov, http://www.deepmd.org, and https://www.sprkkr.org, respectively. VASP is a commercial software package available from https://www.vasp.at. Detailed information on access, installation, and usage of these codes is provided on their respective websites. The input files used in this study are publicly available on Zenodo77 (https://doi.org/10.5281/zenodo.18484546).
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Acknowledgements
J.S. gratefully acknowledges financial support from the National Natural Science Foundation of China (Grant No. 12125404 and T2495231), the Basic Research Program of Jiangsu Province (Grant No. BK20233001 and BK20253009), the Fundamental and Interdisciplinary Disciplines Breakthrough Plan of the Ministry of Education of China, the Science Challenge Project (No. TZ2025013), the AI & AI for Science Program of Nanjing University, the Artificial Intelligence and Quantum Physics (AIQ) Program of Nanjing University, and the Fundamental Research Funds for the Central Universities. The authors gratefully acknowledge computational resources provided by the High-Performance Computing Center of the Collaborative Innovation Center of Advanced Microstructures and the High-Performance Computing Center of Nanjing University. R.E.C. gratefully acknowledges financial support from the U.S. National Science Foundation CSEDI program (Grant No. EAR-1901813) and the Carnegie Institution for Science. The authors acknowledge supercomputing support from the Resnick High Performance Computing Center. The authors also acknowledge the Gauss Center for Supercomputing e.V. (http://www.gauss-centre.eu/) for providing computing time on the GCS Supercomputer SuperMUC-NG at the Leibniz Supercomputing Center (http://www.lrz.de/). We also thank Ján Minár for many helpful discussions on transport property calculations.
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C.L. designed the research and performed the simulations. C.L., R.E.C., and J.S. contributed to data processing, numerical simulations, and analysis. C.L. wrote the first draft of the manuscript, which R.E.C. and J.S. subsequently reviewed and improved.
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Liu, C., Cohen, R.E. & Sun, J. Prediction of thermally driven quasi-1D superionic states in carbon hydride under giant planetary conditions. Nat Commun (2026). https://doi.org/10.1038/s41467-026-70603-z
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DOI: https://doi.org/10.1038/s41467-026-70603-z
