The behavior of methane-water mixtures under elevated pressures from simulations using many-body potentials.
J Chem Phys
; 156(19): 194504, 2022 May 21.
Article
em En
| MEDLINE
| ID: mdl-35597630
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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Base de dados:
MEDLINE
Idioma:
En
Revista:
J Chem Phys
Ano de publicação:
2022
Tipo de documento:
Article
País de afiliação:
Itália