Critical points, phase transitions and water-like anomalies for an isotropic two length scale potential with increasing attractive well

TL;DR

This study investigates how varying the attraction in a two-length-scale core-softened potential affects water-like anomalies, phase transitions, and critical points, revealing that increased attraction shifts phase boundaries and influences transition behaviors.

Contribution

It introduces a family of core-softened potentials with adjustable attraction, analyzing their impact on phase behavior and anomalies, and highlights the Ising-like nature of the liquid-gas transition across parameters.

Findings

Density, diffusion, and structural anomalies shrink with increased attraction.

Liquid-liquid transition arises from non-monotonic density-pressure behavior.

Liquid-gas critical temperature rises with attraction strength.

Abstract

Molecular Dynamic and Monte Carlo studies are performed in a family of core-softened (CS) potential, composed by two length scales: a repulsive shoulder at short distances and the another a variable scale, that can be repulsive or strongly attractive depending on the parameters used. The density, diffusion and structural anomalous regions in the pressure versus temperature phase diagram shrink in pressure as the system becomes more attractive. The liquid-liquid transition appears as a consequence of the non monotonic behavior of the density versus pressure isotherms with the increase of the attraction well. We found that the liquid-gas phase transition is Ising-like for all the CS potentials and its critical temperature increases with the increase of the attraction. No Ising-like behavior for the liquid-liquid phase transition was detected in the Monte Carlo simulations what might be due to the presence of stable solid phases.