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Liquid-Liquid Criticality in TIP4P/2005 and Three-State Models of Water
Claudio A Cerdeiriña1, Diego González-Salgado1, Jacobo Troncoso1
1Instituto de Física e Ciencias Aeroespaciais da Universidade de Vigo and Unidad MSMN Asociada al CSIC por el IQFR, Ourense 32004, Spain.
The Journal of Physical Chemistry. B
|April 25, 2023
Summary
Molecular dynamics simulations confirm TIP4P/2005 water
Area of Science:
- Thermodynamics
- Computational Chemistry
- Statistical Mechanics
Background:
- Water exhibits complex phase behavior, including a hypothesized second liquid-liquid critical point.
- Understanding this critical point is crucial for explaining water's anomalous properties.
Purpose of the Study:
- To investigate the thermodynamic response functions of TIP4P/2005 water near its liquid-liquid critical point.
- To compare simulation results with theoretical predictions of critical phenomena.
- To distinguish liquid-liquid criticality from gas-liquid criticality.
Main Methods:
- Molecular dynamics simulations of TIP4P/2005 water.
- Calculation of isothermal compressibility, isobaric thermal expansivity, and isobaric heat capacity.
- Analysis of response-function ratios.
- Comparison with a three-state Ising model.
Main Results:
- Simulation results for TIP4P/2005 water are consistent with the reported liquid-liquid critical point.
- Response functions show marked increases along the critical isochore as temperature decreases.
- Response-function ratios reveal nonuniversal features, distinguishing liquid-liquid from gas-liquid criticality.
Conclusions:
- Molecular dynamics simulations support the existence and characteristics of water's second critical point.
- The behavior near the liquid-liquid critical point aligns with critical phenomena theory and exhibits unique features compared to gas-liquid criticality.
- The findings are qualitatively consistent with a three-state Ising model for water.
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