On the different faces of the supercritical phase of water at a near-critical temperature: pressure-induced structural transitions ranging from a gaslike fluid to a plastic crystal polymorph
The present study reports a systematic analysis of a wide variety of structural, thermodynamic, and dynamic properties of supercritical water along the near-critical isotherm of T = 1.03Tc and up to extreme pressures, using molecular dynamics and Monte Carlo simulations. The methodology employed pro...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/359088 |
| Acceso en línea: | https://hdl.handle.net/2117/359088 https://dx.doi.org/10.1021/acs.jpcb.1c05053 |
| Access Level: | acceso abierto |
| Palabra clave: | Crystals Plastics Structural dynamics Molecules Phase transitions Cristalls Plàstics Dinàmica estructural Molècules Àrees temàtiques de la UPC::Física |
| Sumario: | The present study reports a systematic analysis of a wide variety of structural, thermodynamic, and dynamic properties of supercritical water along the near-critical isotherm of T = 1.03Tc and up to extreme pressures, using molecular dynamics and Monte Carlo simulations. The methodology employed provides solid evidence about the existence of a structural transition from a liquidlike fluid to a compressed, tightly packed liquid, in the density and pressure region around 3.4¿c and 1.17 GPa, introducing an alternative approach to locate the crossing of the Frenkel line. Around 8.5 GPa another transition to a face-centered-cubic plastic crystal polymorph with density 5.178¿c is also observed, further confirmed by Gibbs free energy calculations using the two-phase thermodynamic model. The isobaric heat capacity maximum, closely related to the crossing of the Widom line, has also been observed around 0.8¿c, where the local density augmentation is also maximized. Another structural transition has been observed at 0.2¿c, related to the transformation of the fluid to a dilute gas at lower densities. These findings indicate that a near-critical isotherm can be divided into different domains where supercritical water exhibits distinct behavior, ranging from a gaslike one to a plastic crystal one. |
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