Signatures of Water Dissociation at Extreme Conditions in Vibrational Spectra and Ionic Conductivity from ab initio Simulations

POSTER

Abstract

Predicting the properties of water at high pressure and~temperature is critical to understanding hydrogen bonding, charge transport, and phase stability of aqueous media in the Earth and outer planets. Here we employed ab initio molecular dynamics and density functional perturbation theory, as implemented in the Qbox code [1] to study ionic conductivity and infrared and Raman spectra of water at 10 and 20 GPa and 1000 K, as well as those of an amorphous solid phase at 16 GPa, and 500K. We identified specific signatures of proton hopping and molecular dissociation in the IR spectra at 20 GPa, which may be used to guide future experiments, as well as signatures of molecular diffusivity in the low frequency portion of Raman spectra, which help discern between amorphous and liquid phases at high pressure. We also computed ionic conductivities using~maximally localized Wannier functions. We used our results at~ 20 GPa and~ 1000 K to address the existence of possible plastic and~ amorphous ice phases, recently proposed to potentially mediate the ice VII melting line. \newline [1] http://qboxcode.org

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Authors

  • Viktor Rozsa

    University of Chicago

  • Ding Pan

    Hong Kong University of Science and Technology, Department of Physics and Department of Chemistry, Hong Kong University of Science and Technology

  • Giulia Galli

    Univ of Chicago and Argonne National Laboratory, Univ of Chicago, University of Chicago; Argonne National Laboratory, Institute for Molecular Engineering, University of Chicago; Argonne National Laboratory, Institute for Molecular Engineering, University of Chicago and Materials Science Division, Argonne Natl Lab, Institute for Molecular Engineering, University of Chicago; Materials Science Division, Argonne National Laboratory, Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637 and Materials Science Division, Argonne National Laboratory, Lemont, IL, Institute for Molecular Engineering, University of Chicago and Argonne Natl Lab, University of Chicago, Chicago, IL 60637, USA, The University of Chicago, Institute for Molecular Engineering and Argonne National Laboratory, Argonne National Laboratory and University of Chicago, Institute for Molecular Engineering, University of Chicago and Materials Science Division, Argonne National Laboratory, University of Chicago, The University of Chicago, University of Chicago and Argonne National Laboratory