Dissociation of salts in water under pressure
| Autor: | Giulia Galli, Juan J. de Pablo, Cunzhi Zhang, Francois Gygi, Emre Sevgen, Federico Giberti |
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| Rok vydání: | 2020 |
| Předmět: |
Materials science
Science General Physics and Astronomy Dielectric Molecular dynamics 010402 general chemistry 01 natural sciences General Biochemistry Genetics and Molecular Biology Dissociation (chemistry) Mantle (geology) Article Metastability 0103 physical sciences Planetary science Computational methods Physics::Chemical Physics lcsh:Science Minimum free energy Multidisciplinary Aqueous solution 010304 chemical physics General Chemistry Relative stability 0104 chemical sciences Chemical physics lcsh:Q |
| Zdroj: | Nature communications, vol 11, iss 1 Nature Communications Nature Communications, Vol 11, Iss 1, Pp 1-9 (2020) |
| Popis: | The investigation of salts in water at extreme conditions is crucial to understanding the properties of aqueous fluids in the Earth. We report first principles (FP) and classical molecular dynamics simulations of NaCl in the dilute limit, at temperatures and pressures relevant to the Earth’s upper mantle. Similar to ambient conditions, we observe two metastable states of the salt: the contact (CIP) and the solvent-shared ion-pair (SIP), which are entropically and enthalpically favored, respectively. We find that the free energy barrier between the CIP and SIP minima increases at extreme conditions, and that the stability of the CIP is enhanced in FP simulations, consistent with the decrease of the dielectric constant of water. The minimum free energy path between the CIP and SIP becomes smoother at high pressure, and the relative stability of the two configurations is affected by water self-dissociation, which can only be described properly by FP simulations. Salts in water at extreme conditions play a fundamental role in determining the properties of the Earthʼs mantle constituents. Here the authors shed light on ion-water and ion-ion interactions for NaCl dissolved in water at conditions relevant to the Earthʼs upper mantle by molecular dynamics simulations. |
| Databáze: | OpenAIRE |
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