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Robinson VN, Ghosh R, Egan CK, Riera M, Knight C, Paesani F, Hassanali A. The behavior of methane-water mixtures under elevated pressures from simulations using many-body potentials. J Chem Phys 2022; 156:194504. [PMID: 35597630 DOI: 10.1063/5.0089773] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Non-polarizable empirical potentials have been proven to be incapable of capturing the mixing of methane-water mixtures at elevated pressures. Although density functional theory-based ab initio simulations may circumvent this discrepancy, they are limited in terms of the relevant time and length scales associated with mixing phenomena. Here, we show that the many-body MB-nrg potential, designed to reproduce methane-water interactions with coupled cluster accuracy, successfully captures this phenomenon up to 3 GPa and 500 K with varying methane concentrations. Two-phase simulations and long time scales that are required to fully capture the mixing, affordable due to the speed and accuracy of the MBX software, are assessed. Constructing the methane-water equation of state across the phase diagram shows that the stable mixtures are denser than the sum of their parts at a given pressure and temperature. We find that many-body polarization plays a central role, enhancing the induced dipole moments of methane by 0.20 D during mixing under pressure. Overall, the mixed system adopts a denser state, which involves a significant enthalpic driving force as elucidated by a systematic many-body energy decomposition analysis.
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Affiliation(s)
- Victor Naden Robinson
- The 'Abdus Salam' International Centre for Theoretical Physics, I-34151 Trieste, Italy
| | - Raja Ghosh
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
| | - Colin K Egan
- The 'Abdus Salam' International Centre for Theoretical Physics, I-34151 Trieste, Italy
| | - Marc Riera
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
| | - Christopher Knight
- Computational Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, USA
| | - Francesco Paesani
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
| | - Ali Hassanali
- The 'Abdus Salam' International Centre for Theoretical Physics, I-34151 Trieste, Italy
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Pruteanu CG, Robinson VN, Hassanali AA, Scandolo S, Loveday J, Ackland G. How to determine solubility in binary mixtures from Neutron Scattering data: the case of methane and water. J Chem Phys 2022; 156:054502. [DOI: 10.1063/5.0077912] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ciprian Gabriel Pruteanu
- Physics and Astronomy, The University of Edinburgh School of Physics and Astronomy, United Kingdom
| | - Victor Naden Robinson
- Abdus Salam International Centre for Theoretical Physics Condensed Matter and Statistical Physics Section, Italy
| | | | | | - John Loveday
- School of Physics and Astronomy, University of Edinburgh, United Kingdom
| | - Graeme Ackland
- Department of Physics and Astronomy, The University of Edinburgh, United Kingdom
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Pruteanu CG, Naden Robinson V, Ansari N, Hassanali A, Scandolo S, Loveday JS. Squeezing Oil into Water under Pressure: Inverting the Hydrophobic Effect. J Phys Chem Lett 2020; 11:4826-4833. [PMID: 32496780 PMCID: PMC7467747 DOI: 10.1021/acs.jpclett.0c01410] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 06/04/2020] [Indexed: 06/11/2023]
Abstract
The molecular structure of dense homogeneous fluid water-methane mixtures has been determined for the first time using high-pressure neutron-scattering techniques at 1.7 and 2.2 GPa. A mixed state with a fully H-bonded water network is revealed. The hydration shell of the methane molecules is, however, revealed to be pressure-dependent with an increase in the water coordination between 1.7 and 2.2 GPa. In parallel, ab initio molecular dynamics simulations have been performed to provide insight into the microscopic mechanisms associated with the phenomenon of mixing. These calculations reproduce the observed phase change from phase separation to mixing with increasing pressure. The calculations also reproduce the experimentally observed structural properties. Unexpectedly, the simulations show mixing is accompanied by a subtle enhancement of the polarization of methane. Our results highlight the key role played by fine electronic effects on miscibility and the need to readjust our fundamental understanding of hydrophobicity to account for these.
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Affiliation(s)
- Ciprian G. Pruteanu
- Department
of Physics and Astronomy, University College
London, Gower Street, London WC1E
6BT, United Kingdom
| | - Victor Naden Robinson
- The
“Abdus Salam” International Centre for Theoretical Physics, I-34151 Trieste, Italy
| | - Narjes Ansari
- The
“Abdus Salam” International Centre for Theoretical Physics, I-34151 Trieste, Italy
| | - Ali Hassanali
- The
“Abdus Salam” International Centre for Theoretical Physics, I-34151 Trieste, Italy
| | - Sandro Scandolo
- The
“Abdus Salam” International Centre for Theoretical Physics, I-34151 Trieste, Italy
| | - John S. Loveday
- SUPA,
School of Physics and Astronomy and Centre for Science at Extreme
Conditions, The University of Edinburgh, Edinburgh EH9 3JZ, United Kingdom
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Lu M, Zhou D, Li F, Liang Y, Zhou Q, Huang X, Cui T. Disorder-order structural transition of single crystal hydrogen chloride under high pressure-temperature. Phys Chem Chem Phys 2019; 21:17655-17661. [PMID: 31364643 DOI: 10.1039/c9cp02839k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydrogen chloride (HCl) is the simplest hydrogen-bonded molecule and has attracted a great deal of attention owing to its interesting structural changes triggered by pressure or temperature. The structural properties of solid HCl have been investigated by Brillouin scattering in the pressure range of 0-20 GPa under high temperature, combined with external heating in a diamond anvil cell. Three elastic constants and two moduli of the single crystal sample were observed at high pressure-temperature and each of them grows monotonously with pressure along a separate isotherm. The pressure dependence of elastic anisotropy proves that the disorder-order transition pressures are 4.5 GPa, 5.4 GPa and 8.8 GPa for the 300 K, 390 K and 470 K isotherms, respectively. The current work discovered the disorder-order structural transition in HCl and extended its phase diagram to the high pressure-temperature range, also providing a new insight into other simple hydrogen-bonded molecular compounds.
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Affiliation(s)
- Mengya Lu
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, People's Republic of China.
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Pruteanu CG, Ackland GJ, Poon WCK, Loveday JS. When immiscible becomes miscible-Methane in water at high pressures. SCIENCE ADVANCES 2017; 3:e1700240. [PMID: 28845447 PMCID: PMC5567757 DOI: 10.1126/sciadv.1700240] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 07/26/2017] [Indexed: 05/06/2023]
Abstract
At low pressures, the solubility of gases in liquids is governed by Henry's law, which states that the saturated solubility of a gas in a liquid is proportional to the partial pressure of the gas. As the pressure increases, most gases depart from this ideal behavior in a sublinear fashion, leveling off at pressures in the 1- to 5-kbar (0.1 to 0.5 GPa) range with solubilities of less than 1 mole percent (mol %). This contrasts strikingly with the well-known marked increase in solubility of simple gases in water at high temperature associated with the critical point (647 K and 212 bar). The solubility of the smallest hydrocarbon, the simple gas methane, in water under a range of pressure and temperature is of widespread importance, because it is a paradigmatic hydrophobe and occurs widely in terrestrial and extraterrestrial geology. We report measurements up to 3.5 GPa of the pressure dependence of the solubility of methane in water at 100°C-well below the latter's critical temperature. Our results reveal a marked increase in solubility between 1 and 2 GPa, leading to a state above 2 GPa where the maximum solubility of methane in water exceeds 35 mol %.
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6
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Wang X, Chen C, Huang X, Wang J, Yao M, Wang K, Huang F, Han B, Zhou Q, Li F. Acoustic and elastic properties of silicone oil under high pressure. RSC Adv 2015. [DOI: 10.1039/c5ra03817k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Brillouin scattering spectra of three silicone oils with different viscosity, including two polydimethylsiloxanes (PDMS) and one polyphenylmethylsiloxane (PPMS), have been studied under high pressure.
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Liu B, Yang J, Wang Q, Han Y, Ma Y, Gao C. Determination of the phase diagram of water and investigation of the electrical transport properties of ices VI and VII. Phys Chem Chem Phys 2013; 15:14364-9. [PMID: 23880979 DOI: 10.1039/c3cp51988k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The phase diagram of water near the ice VI-ice VII-liquid triple point and electrical transport properties of these ices have been studied by in situ electrical conductivity measurements in a diamond anvil cell. The obtained phase boundary between ices VI and VII and the melting curve for these ices are in accord with most previous results. The different properties and amount of orientational defects in ice VI and ice VII are associated with abrupt changes in conductivity when a phase transition from ice VI to ice VII occurs. The electrical transport mechanisms of these two ice polymorphs can be understood in terms of the conduction of the already existing ions and Bjerrum defects.
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Affiliation(s)
- Bao Liu
- College of Science, Northeast Dianli University, No 169 Changchun Road, Jilin 132012, China.
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Sanchez-Valle C, Mantegazzi D, Bass JD, Reusser E. Equation of state, refractive index and polarizability of compressed water to 7 GPa and 673 K. J Chem Phys 2013; 138:054505. [PMID: 23406131 DOI: 10.1063/1.4789359] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The equation of state (EoS), refractive index n, and polarizability α of water have been determined up to 673 K and 7 GPa from acoustic velocity measurements conducted in a resistively heated diamond anvil cell using Brillouin scattering spectroscopy. Measured acoustic velocities compare favorably with previous experimental studies but they are lower than velocities calculated from the extrapolation of the IAPWS95 equation of state above 3 GPa at 673 K and deviations increase up to 6% at 7 GPa. Densities calculated from the velocity data were used to propose an empirical EoS suitable in the 0.6-7 GPa and 293-673 K range with a total estimated uncertainty of 0.5% or less. The density model and thermodynamic properties derived from the experimental EoS have been compared to several EoS proposed in the literature. The IAPWS95 EoS provides good agreement, although underestimates density by up to 1.2% at 7 GPa and 673 K and the thermodynamic properties deviate greatly (10%-20%) outside the estimated uncertainties above 4 GPa. The refractive index n of liquid water increases linearly with density and do not depend intrinsically on temperature. The polarizability decreases with pressure by less than 4% within the investigated P-T range, suggesting strong intermolecular interactions in H(2)O that are consistent with the prevalence of the hydrogen bond network in the fluid. The results will allow the refinement of interaction potentials that consider polarization effects for a better understanding of solvent-solvent and ion-solvent interactions in aqueous fluids at high pressure and temperature conditions.
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Mantegazzi D, Sanchez-Valle C, Reusser E, Driesner T. Thermodynamic properties of aqueous sodium sulfate solutions to 773 K and 3 GPa derived from acoustic velocity measurements in the diamond anvil cell. J Chem Phys 2012; 137:224501. [PMID: 23249011 DOI: 10.1063/1.4769265] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The thermodynamic properties of a 1 m Na(2)SO(4) solution have been determined to 773 K and 3 GPa from acoustic velocity measurements in externally heated diamond anvil cell using Brillouin spectroscopy. The measured acoustic velocities were inverted to obtain the density of the aqueous electrolyte solution with an accuracy of 0.3%-0.5%, and an equation of state (EoS) valid in the 293-773 K and 0.4-3 GPa range is proposed. The new EoS reproduces the experimental acoustic velocity data with a maximal deviation of 1.5% and allows deriving all thermodynamic properties of the aqueous solution, including isobaric heat capacity (C(P)), thermal expansion (α(P)), and compressibility (β) with an accuracy better than 3%-8%. The addition of dissolved sulfate species decreases the compressibility of water, consistent with the structure-maker character of SO(4)(2-) ions in solution that enhance the hydrogen-bond network of the solvent.
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Affiliation(s)
- Davide Mantegazzi
- Institute for Geochemistry and Petrology, ETH Zurich, Clausiusstrasse 25, 8092 Zurich, Switzerland.
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Ma C, Wu X, Huang F, Zhou Q, Li F, Cui Q. The acoustic velocity, refractive index, and equation of state of liquid ammonia dihydrate under high pressure and high temperature. J Chem Phys 2012; 137:104504. [PMID: 22979871 DOI: 10.1063/1.4751944] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
High-pressure and high-temperature Brillouin scattering studies have been performed on liquid of composition corresponding to the ammonia dihydrate stoichiometry (NH(3)·2H(2)O) in a diamond anvil cell. Using the measured Brillouin frequency shifts from 180° back- and 60° platelet-scattering geometries, the acoustic velocity, refractive index, density, and adiabatic bulk modulus have been determined under pressure up to freezing point along the 296, 338, 376, and 407 K isotherms. Along these four isotherms, the acoustic velocities increase smoothly with increasing pressure but decrease with the increased temperature. However, the pressure dependence of the refractive indexes on the four isotherms exhibits a change in slope around 1.5 GPa. The bulk modulus increases linearly with pressure and its slope, dB/dP, decreases from 6.83 at 296 K to 4.41 at 407 K. These new datasets improve our understanding of the pressure- and temperature-induced molecular structure changes in the ammonia-water binary system.
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Affiliation(s)
- Chunli Ma
- State Key Laboratory of Superhard Materials, Jilin University, Changchun, 130012 People's Republic of China
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