Path-integral simulation of ice VII: Pressure and temperature effects

Herrero, Carlos P.; Ramı́rez, Rafael

doi:10.1016/j.chemphys.2015.09.011

Cited by 12 publications

(7 citation statements)

References 104 publications

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“…In stage II, under a large f p , f H goes across the curvature turning point, leading to the shrinks of both O:H and O-H. Intermediate phases exist during the transition where proton disordered symmetrization occurs with delocalized proton in a relatively broad potential well. The delocalization of proton (or proton-transfer) may attributed to quantum effect of nuclei1639, or to thermal fluctuations obtained by AIMD15. In this work, we focus on the proton centring due to electron interactions within the O:H-O bond.…”

Section: Potential Model Proposedmentioning

confidence: 99%

Hydrogen-bond potential for ice VIII-X phase transition

Zhang

Chen

2016

Sci Rep

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Repulsive force between the O-H bonding electrons and the O:H nonbonding pair within hydrogen bond (O-H:O) is an often overlooked interaction which dictates the extraordinary recoverability and sensitivity of water and ice. Here, we present a potential model for this hidden force opposing ice compression of ice VIII-X phase transition based on the density functional theory (DFT) and neutron scattering observations. We consider the H-O bond covalent force, the O:H nonbond dispersion force, and the hidden force to approach equilibrium under compression. Due to the charge polarization within the O:H-O bond, the curvatures of the H-O bond and the O:H nonbond potentials show opposite sign before transition, resulting in the asymmetric relaxation of H-O and O:H (O:H contraction and H-O elongation) and the H+ proton centralization towards phase X. When cross the VIII-X phase boundary, both H-O and O:H contract slightly. The potential model reproduces the VIII-X phase transition as observed in experiment. Development of the potential model may provide a choice for further calculations of water anomalies.

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Section: Potential Model Proposedmentioning

confidence: 99%

Hydrogen-bond potential for ice VIII-X phase transition

Zhang

Chen

2016

Sci Rep

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“…Quantum delocalisation is also key to order-disorder transitions in hydrogen-bonded crystals. This includes high pressure phases of ice [43,168,178] and certain organic crystals where the order-disorder transition is connected with an (anti-)ferroelectric to paraelectric transition. One system of particular interest that we have looked at recently is squaric acid [7].…”

Section: A Quantum Delocalisation In Hydrogen Bondsmentioning

confidence: 99%

The quantum nature of hydrogen

Fang

Chen

Feng

et al. 2019

International Reviews in Physical Chemistry

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Hydrogen is the most abundant element. It is also the most quantum, in the sense that quantum tunnelling, quantum delocalisation, and zero-point motion can be important. For practical reasons most computer simulations of materials have not taken such effects into account, rather they have treated nuclei as classical particles. However, thanks to methodological developments over the last few decades, nuclear quantum effects can now be treated in complex materials. Here we discuss our studies on the role nuclear quantum effects play in hydrogen containing systems. We give examples of how the quantum nature of the nuclei has a significant impact on the location of the boundaries between phases in high pressure condensed hydrogen. We show how nuclear quantum effects facilitate the dissociative adsorption of molecular hydrogen on solid surfaces and the diffusion of atomic hydrogen across surfaces. Finally, we discuss how nuclear quantum effects alter the strength and structure of hydrogen bonds, including those in DNA. Overall these studies demonstrate that nuclear quantum effects can manifest in different, interesting, and non-intuitive ways. Whilst historically it has been difficult to know in advance what influence nuclear quantum effects will have, some of the important conceptual foundations have now started to emerge.

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“…These were found in cases such as protein hydration shell water 19 and in water nanoconfined in silica gels, 20,21 in carbon nanotubes 22 and in Beryl. 23 These anomalies couldn't be captured however by the SE approach nor by more sophisticated theoretical calculations such as path integral molecular dynamics (PIMD) 24,25,26 and path integral monte Carlo (PIMC) 27,28,29,26 calculations. Only very recently, a first success was reported by utilizing first principle based DFT simulations of the partial H-VDOS in the H2O@Berryl system.…”

Section: Pvdos Vs Sementioning

confidence: 99%

Anisotropy of the proton kinetic energy in ice Ih

Finkelstein¹,

Moreh

Bianchini

et al. 2019

Surface Science

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The partial vibrational density of states (pVDOS) of ice Ih, as simulated by first principle modeling based on density functional theory (DFT), is utilized for computing the Cartesian components of the proton and oxygen quantum kinetic energies, Ke(H) and Ke(O) respectively, along and perpendicular to the hydrogen bonds. The DFT method was found to yield better agreement with deep inelastic neutron scattering (DINS) measurements than the semi empirical (SE) calculations. The advantage of using the DFT method is to enable us to resolve the external and internal phonon bands of the Cartesian projections of the pVDOS, and hence those of the lattice and vibrational components of Ke(H). We show that a pVDOS analysis is a valuable tool in testing scattering results of complex systems and suggest its potential to explore competing quantum effects, e.g. on Ke(H) across phase transitions in water.

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Path-integral simulation of ice VII: Pressure and temperature effects

Cited by 12 publications

References 104 publications

Hydrogen-bond potential for ice VIII-X phase transition

Hydrogen-bond potential for ice VIII-X phase transition

The quantum nature of hydrogen

Anisotropy of the proton kinetic energy in ice Ih

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