Single-Crystal Neutron Diffraction Studies of the Structure of Ice XI

Jackson, Suzanne F.; Nield, V. M.; Whitworth, R. W.; Oguro, Mitsugu; Wilson, Chick C.

doi:10.1021/jp9632551

Cited by 127 publications

(105 citation statements)

References 19 publications

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“…In this structure, all the c-axis hydrogen bonds are inverse mirror and all the others are, interestingly, the presumably higher energy inverse center. 24,25 Thus this proton ordered phase is not what would be predicted based in optimal dimer geometries. A proton ordered structure with a Pna2 1 space group in which all hydrogen bonds are inverse mirror and oblique center can be constructed.…”

Section: Introductionmentioning

confidence: 86%

“…For that structure, all hydrogen bonds along the c-axis point in the same direction and all hydrogen bonds in a single hexagonal layer are along the same direction as well. 24,25 So a closed hydrogen bonded loop in which each molecule contributes one and only one hydrogen bond to the loop cannot be constructed without crossing to the next periodic image-hydrogen bond paths along any direction are parallel one-way streets in the Cmc2 1 structure. In the Pna2 1 and proton disordered structure, smaller loops within the central simulation box can be generated and the smaller loops have a higher acceptance probability.…”

Section: A Hydrogen Bond Order Parameters: Temperature Dependence Tmentioning

confidence: 99%

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Simulations of proton order and disorder in ice Ih

Rick

2005

The Journal of Chemical Physics

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Computer simulations of ice Ih with different proton orientations are presented. Simulations of proton disordered ice are carried out using a Monte Carlo method which samples over proton degree of freedom, allowing for the calculation of the dielectric constant and for the examination of the degree of proton disorder. Simulations are also presented for two proton ordered structures of ice Ih, the ferroelectric Cmc2 1 structure or ice XI and the antiferroelectric Pna2 1 structure. These simulations indicate that a transition to a proton ordered phase occurs at low temperatures ͑below 80 K͒. The symmetry of the ordered phase is found to be dependent on the water potential. The stability of the two proton ordered structures is due to a balance of short-ranged interactions which tend to stabilize the Pna2 1 structure and longer-range interactions which stabilize the Cmc2 1 structure.

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Section: Introductionmentioning

confidence: 86%

Section: A Hydrogen Bond Order Parameters: Temperature Dependence Tmentioning

confidence: 99%

Simulations of proton order and disorder in ice Ih

Rick

2005

The Journal of Chemical Physics

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“…Specific heat measurements in KOH doped ice showed a strong and highly hysteretic first order phase transition with a substantial loss of entropy in the low temperature phase 46 . Neutron scattering experiments on single crystals of ice have confirmed the ordering transition 49,50 . While the critical temperature is weakly dependent on the amount of KOH, the loss of entropy is dependent on the KOH concentration.…”

Section: Conclusion and Experimental Realizationsmentioning

confidence: 96%

Ice: A strongly correlated proton system

2006

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We discuss the problem of proton motion in Hydrogen bond materials with special focus on ice. We show that phenomenological models proposed in the past for the study of ice can be recast in terms of microscopic models in close relationship to the ones used to study the physics of MottHubbard insulators. We discuss the physics of the paramagnetic phase of ice at 1/4 filling (neutral ice) and its mapping to a transverse field Ising model and also to a gauge theory in two and three dimensions. We show that H + 3 O and HO − ions can be either in a confined or deconfined phase. We obtain the phase diagram of the problem as a function of temperature T and proton hopping energy t and find that there are two phases: an ordered insulating phase which results from an order-bydisorder mechanism induced by quantum fluctuations, and a disordered incoherent metallic phase (or plasma). We also discuss the problem of decoherence in the proton motion introduced by the lattice vibrations (phonons) and its effect on the phase diagram. Finally, we suggest that the transition from ice Ih to ice XI observed experimentally in doped ice is the confining-deconfining transition of our phase diagram.

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“…These experiments are challenging and have lead to a wide range (6K-127K) of estimates for T C , as reviewed in Ref. 15 and neutron diffraction has provided the crystal symmetry (Cmc2 1 ) of the ice XI phase 19,20 . The dielectric tensor should thus be considered a quantity that is very sensitive to important aspects of water, namely the polarization of the system, and the detailed energetics of the various hydrogen bonding configurations.…”

Section: Introductionmentioning

confidence: 99%

Dielectric Properties of Water Ice, the Ice Ih/XI Phase Transition, and an Assessment of Density Functional Theory

et al. 2014

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The dielectric properties of the hydrogen disordered hexagonal phase (Ih) of water ice have been computed using density functional theory (DFT) based Monte Carlo simulations in the isobaric isothermal ensemble. Temperature dependent data yield a fit for the Curie-Weiss law of the system and hence a prediction of the temperature of the phase transition from the Ih phase to the hydrogen ordered ice XI phase. Direct simulations around the phase transition temperature confirm and refine the predicted phase transition temperatures and provide data for further properties, such as the linear thermal expansion coefficient. Results have been obtained with both hybrid and semilocal density functionals, which yields insight in the performance of the electronic structure method. In particular, the hybrid functional yields significantly more realistic dielectric constants than the semilocal variant, namely epsilon approximate to 116 as opposed to epsilon approximate to 151 at 273 K (epsilon(experiment) = 95). This can be attributed to the tendency of semilocal functionals to be biased to configurations with a large dipole moment, and their overestimation of the dipole moments of these configurations. This is also reflected in the estimates of the Ih/XI transition temperature, which is 70-80 and 90-100 K for the hybrid and semilocal functional respectively. DFT based sampling of the millions of configurations necessary for this work has been enabled by a Tree Monte Carlo algorithm, designed for massively parallel computers. with both hybrid and semi-local density functionals, which yields insight in the performance of the electronic structure method. In particular, the hybrid functional yields significantly more realistic dielectric constants than the semi-local variant, namely ε ≈ 116 as opposed to ε ≈ 151 at 273K (ε experiment = 95). This can be attributed to the tendency of semi-local functionals to be biased to configurations with a large dipole moment, and their overestimation of the dipole moments of these configurations. This is also reflected in the estimates of the Ih/XI transition temperature, which is 70-80K and 90-100K for the hybrid and semi-local functional respectively.DFT based sampling of the millions of configurations necessary for this work has been enabled by a Tree Monte Carlo algorithm, designed for massively parallel computers.

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Single-Crystal Neutron Diffraction Studies of the Structure of Ice XI

Cited by 127 publications

References 19 publications

Simulations of proton order and disorder in ice Ih

Simulations of proton order and disorder in ice Ih

Ice: A strongly correlated proton system

Dielectric Properties of Water Ice, the Ice Ih/XI Phase Transition, and an Assessment of Density Functional Theory

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