Liquid-vapor critical behavior of the TIP4P/2005 water model: effects of NaCl solutes and hydrophobic confinement

Fuente: arXiv
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Main Authors: Sharma, Mayank, Virnau, Peter
Format: Preprint
Published: 2026
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author Sharma, Mayank
Virnau, Peter
author_facet Sharma, Mayank
Virnau, Peter
contents The liquid-vapor critical behavior of water is strongly influenced by both ionic solutes and confinement. Molecular dynamics simulations of aqueous NaCl solutions using the TIP4P/2005 water model and the Madrid-2019 ion parameters reveal a systematic increase in the liquid-vapor critical temperature and pressure with salt concentration, consistent with experimental trends. In contrast, confinement between parallel hydrophobic plates leads to a depression of the critical point. The critical temperature was determined from the Binder cumulant crossing in the NVT ensemble, using a recently developed method originally applied to an active Brownian particle system. The reliability of this approach was verified through complementary NPT simulations. We further demonstrate the pronounced sensitivity of the estimated critical point to the van der Waals cutoff distance, underscoring the importance of properly accounting for long-range interactions. Our framework, which employs and tests an adjusted subbox method, can be readily extended to other critical phenomena, including the liquid-liquid critical point of water.
format Preprint
id arxiv_https___arxiv_org_abs_2601_02086
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Liquid-vapor critical behavior of the TIP4P/2005 water model: effects of NaCl solutes and hydrophobic confinement
Sharma, Mayank
Virnau, Peter
Chemical Physics
Soft Condensed Matter
The liquid-vapor critical behavior of water is strongly influenced by both ionic solutes and confinement. Molecular dynamics simulations of aqueous NaCl solutions using the TIP4P/2005 water model and the Madrid-2019 ion parameters reveal a systematic increase in the liquid-vapor critical temperature and pressure with salt concentration, consistent with experimental trends. In contrast, confinement between parallel hydrophobic plates leads to a depression of the critical point. The critical temperature was determined from the Binder cumulant crossing in the NVT ensemble, using a recently developed method originally applied to an active Brownian particle system. The reliability of this approach was verified through complementary NPT simulations. We further demonstrate the pronounced sensitivity of the estimated critical point to the van der Waals cutoff distance, underscoring the importance of properly accounting for long-range interactions. Our framework, which employs and tests an adjusted subbox method, can be readily extended to other critical phenomena, including the liquid-liquid critical point of water.
title Liquid-vapor critical behavior of the TIP4P/2005 water model: effects of NaCl solutes and hydrophobic confinement
topic Chemical Physics
Soft Condensed Matter
url https://arxiv.org/abs/2601.02086