Dataset for manuscript "Equipartition and the temperature of maximum density of TIP4P/2005 water"

Asthagiri, Dilipkumar N.; Pinheiro dos Santos, Thiago J.; Beck, Thomas L.

doi:10.13139/OLCF/2998539

Title: Dataset for manuscript "Equipartition and the temperature of maximum density of TIP4P/2005 water"

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Abstract

We simulate TIP4P/2005 water in the temperature range of 257 K to 318 K with time-steps 0.25, 0.50, 1.00, 2.00, and 4.00 fs. The density-temperature behavior obtained using 0.25 or 0.50 fs are in excellent agreement with each other but differ from those obtained using time-steps that have been shown earlier to lead to a breakdown of equipartition. The temperature of maximum density (TMD) is 277.15 K with time-step 0.25 or 0.50 fs, but is shifted to progressively lower values for longer time-steps, a trend that holds for different thermostat/barostat combinations. Enhancing the water-water dispersion interaction, as has been recommended for simulating disordered proteins in TIP4P/2005, degrades the description of the liquid-vapor phase envelope. We present a simple physically transparent reasoning to highlight the separation of the time-scales between translational and rotational motion. We also develop a metric, Chi, that we term the equipartition anomaly, to detect equipartition violations in simulations that include molecules that are treated as rigid objects. Calculating Chi is shown to be straightforward and sensitive to equipartition violations. A key takeaway from this study is that using sufficiently short time-steps (less than or equal to 0.5 fs) to preserve equipartition is essential for obtaining meaningful liquidmore »« less

Authors:

;

Oak Ridge National Laboratory

Publication Date:: Tue Dec 09 23:00:00 EST 2025

DOE Contract Number:: AC05-00OR22725

Research Org.:: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:: Advanced Scientific Computing Research (ASCR)

Collaborations:: National Energy Research Scientific Computing (NERSC)

Subject:: 36 MATERIALS SCIENCE; 74 ATOMIC AND MOLECULAR PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Molecular Dynamics Simulations; Thermodynamics; statistical mechanics

OSTI Identifier:: 2998539

DOI:: https://doi.org/10.13139/OLCF/2998539

Citation Formats


                    Asthagiri, Dilipkumar N., Pinheiro dos Santos, Thiago J., and Beck, Thomas L. Dataset for manuscript "Equipartition and the temperature of maximum density of TIP4P/2005 water".  United States: N. p., 2025. 
        Web.  doi:10.13139/OLCF/2998539.

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                    Asthagiri, Dilipkumar N., Pinheiro dos Santos, Thiago J., & Beck, Thomas L. Dataset for manuscript "Equipartition and the temperature of maximum density of TIP4P/2005 water".  United States.  doi:https://doi.org/10.13139/OLCF/2998539

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                    Asthagiri, Dilipkumar N., Pinheiro dos Santos, Thiago J., and Beck, Thomas L. 2025.  
"Dataset for manuscript "Equipartition and the temperature of maximum density of TIP4P/2005 water"".  United States.  doi:https://doi.org/10.13139/OLCF/2998539.  https://www.osti.gov/servlets/purl/2998539. Pub date:Tue Dec 09 23:00:00 EST 2025

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@article{osti_2998539,

  title        = {Dataset for manuscript "Equipartition and the temperature of maximum density of TIP4P/2005 water"},

  author       = {Asthagiri, Dilipkumar N. and Pinheiro dos Santos, Thiago J. and Beck, Thomas L.},

  abstractNote = {We simulate TIP4P/2005 water in the temperature range of 257 K to 318 K with time-steps 0.25, 0.50, 1.00, 2.00, and 4.00 fs. The density-temperature behavior obtained using 0.25 or 0.50 fs are in excellent agreement with each other but differ from those obtained using time-steps that have been shown earlier to lead to a breakdown of equipartition. The temperature of maximum density (TMD) is 277.15 K with time-step 0.25 or 0.50 fs, but is shifted to progressively lower values for longer time-steps, a trend that holds for different thermostat/barostat combinations. Enhancing the water-water dispersion interaction, as has been recommended for simulating disordered proteins in TIP4P/2005, degrades the description of the liquid-vapor phase envelope. We present a simple physically transparent reasoning to highlight the separation of the time-scales between translational and rotational motion. We also develop a metric, Chi, that we term the equipartition anomaly, to detect equipartition violations in simulations that include molecules that are treated as rigid objects. Calculating Chi is shown to be straightforward and sensitive to equipartition violations. A key takeaway from this study is that using sufficiently short time-steps (less than or equal to 0.5 fs) to preserve equipartition is essential for obtaining meaningful liquid water properties and for producing reliable simulation data, as correct-ensemble sampling is fundamental to ensure reproducibility across codes and simulation alogrithms. The included dataset provides the raw data used in the preparation of the graphs noted in the manuscript.},

  doi          = {10.13139/OLCF/2998539},

  journal      = {},

  number       = ,

  volume       = ,

  place        = {United States},

  year         = {Tue Dec 09 23:00:00 EST 2025},

  month        = {Tue Dec 09 23:00:00 EST 2025}

}

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DOI: https://doi.org/10.13139/OLCF/2998539

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