High-pressure x-ray diffraction and Raman spectroscopy of ice VIII

Yoshimura, Yukihiro; Stewart, S. T.; Somayazulu, Maddury; Mao, Ho‐kwang; Hemley, Russell J.

doi:10.1063/1.2140277

Cited by 85 publications

(82 citation statements)

References 40 publications

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“…Differences between the phonon density of states of ice VIII obtained at the PBE and vdW-DF2 level of theory are instead minor. Recent Raman measurements of the stretching vibrations [15] indicate that the frequencies are approximately 3350, 3440, and 3470 cm À1 , consistent with our calculations. The bending modes show little change with respect to either phase or functional, and the rotational and translation modes are redshifted when using vdW-DF2, with respect to PBE results.…”

supporting

confidence: 90%

“…[17] by using PBE. The inclusion of the ZPE worsens the agreement with experiment [15], primarily because of the volume overestimate [28]. We note the much better agreement with experiment obtained for the binding energy of ice VIII when using the vdW functional.…”

Section: -2mentioning

confidence: 61%

“…Recent diffusion Monte Carlo (DMC) results [5] yield lattice energies in closest agreement with experiment. They appear to slightly underestimate the equilibrium volume possibly due to the absence of vibrational effects (as discussed below); this yields larger bulk moduli than obtained with other methods, with a value in excellent agreement with experiment for ice VIII [15] but an overestimate of experiment for ice I h .…”

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confidence: 65%

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Dispersion Interactions and Vibrational Effects in Ice as a Function of Pressure: A First Principles Study

Murray

Galli

2012

Phys. Rev. Lett.

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We present a first principles theoretical framework that accurately accounts for several properties of ice, over a wide pressure range. In particular, we show that, by using a recently developed nonlocal van der Waals functional and by taking into account hydrogen zero point motion, one can properly describe the zero temperature equation of state, the vibrational spectra, and the dielectric properties of ice at low pressure and of ice VIII, a stable phase between 2 and 60 GPa. While semilocal density functionals yield a transition pressure from ice XI to VIII that is overestimated by almost an order of magnitude, we find good agreement with experiments when dispersion forces are taken into account. Zero point energy contributions do not alter the computed transition pressure, but they affect structural properties, including equilibrium volumes and bulk moduli. DOI: 10.1103/PhysRevLett.108.105502 PACS numbers: 63.20.dk, 62.50.Àp, 71.15.Mb, 83.80.Nb Ice has an extremely complex phase diagram [1] that has been studied for over a century [2], due to its importance in several disciplines, encompassing physics, chemistry, and earth and atmospheric sciences. However, until about 35 years ago, little was known experimentally about high pressure phases of ice. For example, the first characterization of ice VIII as an antiferroelectric, ordered phase-now known to be stable at low temperature between 2 and 60 GPa-appeared in 1976 [3]. From a theoretical standpoint, the description of the phase diagram and the properties of ice remains a very challenging problem. Recent ab initio calculations [4,5] have reported remarkable progress in describing the equations of state of some ice phases within density functional theory, as well as in computing optical spectra [6,7]. However, no first principles theory has yet successfully predicted with consistent accuracy a wide range of properties encompassing structural, vibrational, and dielectric properties over a broad range of pressures.In this Letter, we focus on ordered ice phases, ice XI, ordered cubic ice I c , and ice VIII. Ice XI and ordered I c are used as models of the stable phase of ice at ambient pressure close to 0 C. We show that a proper account both of dispersion forces and of hydrogen zero point motion are necessary to obtain a consistently accurate description of several properties of ice over a wide pressure range, at low temperature. We thus establish a theoretical framework that can be used to gain insight into the intricate physics of ice as a function of pressure, from first principles.We carried out calculations within density functional theory and compared results obtained with semilocal (PBE [8]) and nonlocal van der Waals (vdW-DF2 [9]) functionals. We used the QUANTUM ESPRESSO package [10] with hard norm-conserving pseudopotentials [11] for both hydrogen and oxygen and a plane-wave energy cutoff of 160 Ry. A 4 Â 4 Â 4 k-point grid was used for each structure.The lattice energies and equilibrium volumes of each phase were calculated by fully relaxing inte...

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Section: -2mentioning

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Dispersion Interactions and Vibrational Effects in Ice as a Function of Pressure: A First Principles Study

Murray

Galli

2012

Phys. Rev. Lett.

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“…This clearly shows competing quantum effects: hydrogen bonding decreases the ZPE associated with stretch and increases that of the bend vibrations. This is also seen in high pressure experiments on ice VIII: with increasing pressure the frequency of the stretch modes decreases and those of the librational modes increase (164,165). In addition, as shown in …”

Section: Isotope Fractionation As a Probe Of Nuclear Quantum Effectssupporting

confidence: 63%

Nuclear Quantum Effects in Water and Aqueous Systems: Experiment, Theory, and Current Challenges

et al. 2016

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Nuclear quantum effects influence the structure and dynamics of hydrogen bonded systems, such as water, which impacts their observed properties with widely varying magnitudes. This review highlights the recent significant developments in the experiment, theory and simulation of nuclear quantum effects in water. Novel experimental techniques, such as deep inelastic neutron scattering, now provide a detailed view of the role of nuclear quantum effects in water's 2 properties. These have been combined with theoretical developments such as the introduction of the competing quantum effects principle that allows the subtle interplay of water's quantum effects and their manifestation in experimental observables to be explained. We discuss how this principle has recently been used to explain the apparent dichotomy in water's isotope effects, which can range from very large to almost nonexistent depending on the property and conditions. We then review the latest major developments in simulation algorithms and theory that have enabled the efficient inclusion of nuclear quantum effects in molecular simulations, permitting their combination with on-the-fly evaluation of the potential energy surface using electronic structure theory. Finally, we identify current challenges and future opportunities in the area.3

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“…X-ray scattering spectra consequently can allow for clear determination of phase boundaries, and provide very clear ways to compare theory and experiment. A number of x-ray studies of ice VII [8][9][10], ice VIII [11] and ice X [12] exist. It has also been suggested that ice VII might exist in cold conducting slabs within the Earth's mantle [13].…”

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confidence: 99%

X-ray scattering intensities of water at extreme pressure and temperature

Goldman

Fried

2007

The Journal of Chemical Physics

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We have calculated the coherent x-ray scattering intensity of several phases of water at 1500 and 2000 K under high pressure, using ab initio Density Functional Theory (DFT). Our calculations span the molecular liquid, ice VII, and superionic solid phases, including the recently predicted symmetrically hydrogen bonded region of the superionic phase. We show that wide angle x-ray scattering intensity could be used to determine phase boundaries between these high pressure phases, and we compare the results for ice VII and superionic water. We compute simulated spectra and provide new atomic scattering form factors for water at extreme conditions, which take into account frequently neglected changes in ionic charge and electron delocalization. We show that our modifed atomic form factors allow for a nearly exact comaprison to the total x-ray scattering intensities calculated from DFT. Finally, we analyze the effect our new form factors have on determination of the oxygen-oxygen radial distribution function.

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High-pressure x-ray diffraction and Raman spectroscopy of ice VIII

Cited by 85 publications

References 40 publications

Dispersion Interactions and Vibrational Effects in Ice as a Function of Pressure: A First Principles Study

Dispersion Interactions and Vibrational Effects in Ice as a Function of Pressure: A First Principles Study

Nuclear Quantum Effects in Water and Aqueous Systems: Experiment, Theory, and Current Challenges

X-ray scattering intensities of water at extreme pressure and temperature

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