Indirect Attractions between Superionic Di-interstitial Protons on Mid-Oxygens in Water at Extreme Conditions: First-Principles Molecular Dynamics Study

Tsumuraya, Kazuo; Tasaka, Tomofumi; Nagayama, Hisashi; Tsumuraya, Mary I.; Tsumuraya, Masato

doi:10.7566/jpsj.83.104708

Cited by 2 publications

(15 citation statements)

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“…The heights of the four density maxima are equal. Whereas the protons around the oxygens were distributed with the T d configuration in the superionic water, 16) the present distribution is isotropic with respect to the h111i directions. There are curved low proton density regions between the density maxima.…”

Section: Computational Detailsmentioning

confidence: 55%

“…The subpeak decompositions of the PDF's with the Gaussian functions have succeeded in a variety of the systems not only in the superionic water 16) and the conductor ¡-CuI 29) but also in other systems, of which the cases are shown in references in the previous paper. 16) 3. Results Figure 2 shows the atom density profile (ADP) on the (110) plane of the superionic hydrogen fluoride.…”

Section: Computational Detailsmentioning

confidence: 99%

“…The radial RT distributions are calculated with the following procedure: 16) At a certain MD step, the distances from the fluorine to the coordinated protons are calculated. Then the flags of the protons turn to be "on", if the distances are within a specified range.…”

Section: Computational Detailsmentioning

confidence: 99%

“…The conductor ¡-CuI was an intermediate electronic state between the ionic crystals and covalent bonded crystals. In a previous paper 16) Tsumuraya et al have elucidated the formation of short-lived H 2 O molecules in the superionic water at an extreme high pressure and a temperature by use of the first principles MD method. In addition to the direct covalent attraction between the immobile oxygens, they found two types of attractions between the ionized oxygens and the superionic protons.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5] The understanding of these is essential not only for the efficient developments of secondary batteries or fuel cells, but also for the identification of the electronic state of the conductors in the solid state physics. The previous paper 16) elucidated a part of these questions on the water where the number ratio of the mobile ions to the immobile ions was two. The present paper elucidates the questions in the hydrogen fluoride where the number ratio is unity.…”

Section: Introductionmentioning

confidence: 99%

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Short-Lived HF Molecules in Superionic Hydrogen Fluoride at Extreme Conditions

2015

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The first principles molecular dynamics study enables us to elucidate the existence of short-lived HF molecules in the superionic hydrogen fluoride at an extreme high pressure and a temperature. Three fourth of the immobile fluorines constructs the molecules with lifetime of 8 fs. The ionized fluorines form weak HF bond with the proton in the nearest HF molecule of which the lifetime is 3 fs. The covalent and the Coulomb bonds between the fluorines and the protons form indirect covalent and indirect Coulomb attractions between the di-interstitial protons on the mid-fluorines. The attractions reduce the Haven's ratio of the protons. The absence of the proton dimers indicates a failure of the caterpillar diffusion model or the Frenkel-Kontorova chain model for the superionic diffusion of the protons. The incompletely ionized cations and anions reduce their Coulomb attractions which induce the sublattice melting of smaller size and smaller mass of the protons than the fluorines. The electronic states of the fluoride are intermediate between the ionic crystals and the covalent bonded molecular crystals. The superionic conductors are classified into three groups: they are molecular type, covalent metalloid type, and metallic type conductors.

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Section: Computational Detailsmentioning

confidence: 55%

Section: Computational Detailsmentioning

confidence: 99%

Section: Computational Detailsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%