Ferroelectric mobile water

Nakamura, Yoshimichi; Ohno, Takahisa

doi:10.1039/c0cp01428a

Cited by 19 publications

(48 citation statements)

References 31 publications

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“…1; similar examples can also be found in Refs. [43,45]. For a temperature of 300 K there are only two conformational transitions connecting the three metastable states within the simulation time of 200 ns.…”

Section: Remd Simulations Of Water Confined Inside Cntsmentioning

confidence: 99%

Molecular dynamics simulations of proton-ordered water confined in low-diameter carbon nanotubes

Schmidt

2015

Phys. Chem. Chem. Phys.

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The present work deals with molecular dynamics simulations of water confined in single-walled carbon nanotubes (CNTs), with emphasis on the proton-ordering of water and its polarization. First, the water occupancy of open-ended armchair and zigzag CNTs immersed in water under ambient NPT conditions is calculated for various water models, and for varying Lennard-Jones parameters of the water-carbon interaction. As a function of the CNT diameter, the water density displays several oscillations before converging to the bulk value. Based on these results, the water structures encapsulated in 10 nm long armchair CNTs (n,n) with 5 ≤ n ≤ 10, are investigated under NVT conditions. Inside the smallest nanotubes (n = 5, 6) highly ferroelectric (FE), quasi-one-dimensional water chains are found while inside the other CNTs water molecules assemble into single-walled ice nanotubes (INTs). There are several, near-degenerate minimum energy INT structures: single helical structures were found for 7 ≤ n ≤ 10, in all cases in FE arrangement. In addition, a double helical INT structure was found for n = 8 with an even higher polarization. Prism-like structures were found only for 8 ≤ n ≤ 10 with various FE, ferrielectric (FI), and antiferroelectric (AF, n = 9, 10) proton ordering. The coexistence of the nearly iso-energetic FE, FI, and AF INT structures separated by high barriers renders the molecular dynamics highly metastable, typically with nanosecond timescales at room temperature. Hence, the replica exchange simulation method is used to obtain populations of different INT states at finite temperatures. Many of the FE INT structures confined in low-diameter CNTs are still prevalent at room temperature. Both helix-helix and helix-prism structural transitions are detected which can be either continuous (around 470 K for n = 8) or discontinuous (at 218 K for n = 9). Also melting-like transitions are found in which the INT structures are disrupted leading to a loss of FE or FI ordering of the water orientations. Also these transitions can be either smooth (for n = 7, 8) or abrupt, first-order transitions, at T = 362 K for n = 9 and at T = 285 K for n = 10.

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Section: Remd Simulations Of Water Confined Inside Cntsmentioning

confidence: 99%

Molecular dynamics simulations of proton-ordered water confined in low-diameter carbon nanotubes

Schmidt

2015

Phys. Chem. Chem. Phys.

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“…In recent years many theoretical and experimental efforts have been devoted to study CW in carbon nanotubes (CNTs). These studies are focused on various aspects such as water and proton conduction, water adsorption, formation of ice-nanotubes and water-nanotube in CNTs [1][2][3][4][5][6][7][8][9]. Some studies by high-resolution electron microscopy have revealed atomic scale interactions between the entrapped liquid phase and wetted graphite walls of CNTs [10].…”

Section: Introductionmentioning

confidence: 98%

Role of lone pair and π-orbital interaction in formation of water nanostructures confined in carbon nanotubes

Chutia¹,

Hamada²,

Tokuyama³

2012

Chemical Physics Letters

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“…It should be noted that a more recent MD study has reported a brand new water phase called 'ferroelectric mobile water (FMW)' (Nakamura & Ohno, 2011, 2012a, 2012b. Though the FMW at first sight appears similar to the immobilized water mentioned above, they are distinct from each other both in molecular structure and in dynamics.…”

Section: Introductionmentioning

confidence: 98%

“…Five independent phases, labeled '0' to '4', are suggested. Phase #4 corresponds to the FMW, the most stable phase (Nakamura & Ohno, 2011). Figure 12b shows unfolded-view snapshots from each phase, which is helpful to understand how the net polarization is digitized.…”

Section: Ferroelectric Mobile Water (Fmw)mentioning

confidence: 99%

“…Such is also the case for H 2 O/CNT simulations. Though the number of H 2 O/CNT simulation studies based on the 5-site models is only a few, their findings that the water molecules are able to self-assemble into double helixes resembling DNA under high pressure (Bai at al., 2006) and that single-domain ferroelectric mobile water is possible at ambient conditions (Nakamura & Ohno, 2011, 2012a, 2012b are all the more outstanding, considering far more numerous studies based on the 3-and 4-site models.…”

Section: Overview Of Water Modelsmentioning

confidence: 99%

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