Thermodynamic and dynamic anomalies for a three-dimensional isotropic core-softened potential

Area of Science:

• Physical Chemistry
• Computational Physics
• Soft Matter Physics

Background:

• Understanding the thermodynamic and dynamic properties of matter is crucial.
• Intermolecular potentials dictate macroscopic behavior.
• Anomalous properties, like those in water, are of significant scientific interest.

Purpose of the Study:

• To investigate the thermodynamic and dynamic properties of particles with a continuous core-softened potential.
• To determine the line of temperatures of maximum density (TMD) and diffusivity extrema in the pressure-temperature phase diagram.
• To compare the observed behavior with that of water.

Main Methods:

• Molecular-dynamics simulations were employed.
• Integral equations, including Rogers-Young, Percus-Yevick, and hypernetted chain closures, were utilized.
• Thermodynamic and dynamic properties were analyzed.

Main Results:

• A maximum in density at constant pressure was observed at a specific temperature.
• The line of temperatures of maximum density (TMD) was mapped.
• The diffusion constant exhibited a maximum and a minimum at specific densities, with the line of extrema located outside the TMD line.
• This behavior was found to be analogous to that of simple point charge/extended water.

Conclusions:

• The continuous core-softened potential can reproduce anomalous thermodynamic and dynamic behaviors.
• The findings provide insights into the relationship between intermolecular potentials and macroscopic properties.
• The study highlights the potential for non-directional potentials to exhibit water-like anomalies.