Structure Search on H<sub>2</sub>-PRE Phase of Solid Hydrogen: Diffusion Monte Carlo Study

ORAL

Abstract






The structural phase diagram of solid hydrogen is important for condensed matter physics and planetary science. However, the different structures in the phase diagram are still debated due to the experimental difficulties at extreme conditions. Therefore, an accurate ab initio structure search is crucial to assist experiment. We used a combination of structural search algorithms, density functional theory and diffusion Monte Carlo methods to study the problem. We eventually found a new stable structure, P21/c-8, stable under high pressures of 400 – 600 GPa. Our predicted pressure range for P21/c-8's appearance correlates well with a phase found experimentally in hydrogen by infrared spectroscopy. In this talk, we will describe the context of our work from the simulation point of view. We will discuss our results in connection with the experimental evidence and other theoretical predictions.





*This work was supported by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. We acknowledge computational resources provided by the Oak Ridge Leadership Computing Facility at Oak Ridge National Laboratory, which is a user facility of the Office of Science of the US Department of Energy under Contract No. DE-AC05-00OR22725, and by the Compute and Data Environment for Science (CADES) at Oak Ridge National Laboratory. We also acknowledge computational resources provided the Research Center for Advanced Computing Infrastructure (RCACI) at JAIST. T.I. is grateful for financial suport from Grant-in-Aid for JSPS Research Fellow (18J12653). K.H. is grateful for financial support from MEXT-KAKENHI (JP16H06439, JP19K05029, JP19H05169, and JP21K03400), and the Air Force Office of Scientific Research (Award Numbers: FA2386-20-1-4036). R.M. is grateful for financial supports from MEXT-KAKENHI (JP19H04692 and JP16KK0097), FLAGSHIP2020 (project nos. hp190169 and hp190167 at K-computer), the Air Force Office of Scientific Research (AFOSR-AOARD/FA2386-17-1-4049;FA2386-19-1-4015), and JSPS Bilateral Joint Projects (JPJSBP120197714).

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Publication: T. Ichibha, Y. Zhang, K. Hongo, R. Maezono, F.A. Reboredo, Phys. Reb. B, 104, 214111 (2021).
DOI: 10.1103/PhysRevB.104.214111

Presenters

  • Ryo Maezono

    • Japan Adv Inst of Sci and Tech
    • JAIST

Authors

  • Tom Ichibha

    • Oak Ridge National Lab

  • Yunwei Zhang

    • Sun Yat-sen University

  • Kenta Hongo

    • Japan Adv Inst of Sci and Tech
    • JAIST

  • Ryo Maezono

    • Japan Adv Inst of Sci and Tech
    • JAIST

  • Fernando A Reboredo

    • Oak Ridge National Lab