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Phase equilibrium of liquid water and hexagonal ice from enhanced sampling molecular dynamics simulations

Pablo M. Piaggi1*, Roberto Car2

1 Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA

2 Department of Chemistry and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA

* Corresponding authors emails: ppiaggi@princeton.edu
DOI10.24435/materialscloud:1g-kb [version v1]

Publication date: Dec 06, 2021

How to cite this record

Pablo M. Piaggi, Roberto Car, Phase equilibrium of liquid water and hexagonal ice from enhanced sampling molecular dynamics simulations, Materials Cloud Archive 2021.209 (2021), doi: 10.24435/materialscloud:1g-kb.

Description

We study the phase equilibrium between liquid water and ice Ih modeled by the TIP4P/Ice interatomic potential using enhanced sampling molecular dynamics simulations. Our approach is based on the calculation of ice Ih-liquid free energy differences from simulations that visit reversibly both phases. The reversible interconversion is achieved by introducing a static bias potential as a function of an order parameter. The order parameter was tailored to crystallize the hexagonal diamond structure of oxygen in ice Ih. We analyze the effect of the system size on the ice Ih-liquid free energy differences, and we obtain a melting temperature of 270 K in the thermodynamic limit. This result is in agreement with estimates from thermodynamic integration (272 K) and coexistence simulations (270 K). Since the order parameter does not include information about the coordinates of the protons, the spontaneously formed solid configurations contain proton disorder as expected for ice Ih.

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Files

File name Size Description
Analyze.ipynb
MD5md5:49080a4a2cf3ec19e1f8994fb5dd6f75
147.1 KiB Jupyter notebook with scripts to analyze the simulations and create the figures
BiasedSimulations-16molecules.zip
MD5md5:000bc114b32ba08e9886e8e48541b43e
175.4 MiB Biased simulations results for system of 16 molecules
BiasedSimulations-96molecules.zip
MD5md5:c7d25b16412f212a6830d9cb81d34c9d
456.5 MiB Biased simulations results for system of 96 molecules
BiasedSimulations-288molecules.zip
MD5md5:aa6473da158e545eb97c3a9f5cbf62fc
165.5 MiB Biased simulations results for system of 288 molecules
Environments.zip
MD5md5:085b0faa7f7520ba7c1053061d75d41d
3.2 KiB Environments for the EnvironmentSimilarity collective variable
Equilibration.zip
MD5md5:d94b919414316c2ee6061528e89c7e32
24.2 MiB Equilibration simulations
README.md
MD5md5:b36061e08d90e29dcc2359cd056522c0
1.2 KiB More details about the contents of the other files

License

Files and data are licensed under the terms of the following license: Creative Commons Attribution 4.0 International.
Metadata, except for email addresses, are licensed under the Creative Commons Attribution Share-Alike 4.0 International license.

External references

Journal reference (Paper in which the method is described)

Keywords

enhanced sampling ice water proton disorder free energy SNSF

Version history:

2021.209 (version v1) [This version] Dec 06, 2021 DOI10.24435/materialscloud:1g-kb