Multiple liquid-liquid critical points and anomalies in core-softened potentials

TL;DR

This study explores how core-softened potentials in fluids lead to multiple liquid-liquid critical points and density anomalies, using exactly solvable models and molecular dynamics simulations.

Contribution

It demonstrates the existence of three liquid phases and links density anomalies to liquid-liquid phase transitions in core-softened potentials.

Findings

Presence of three liquid phases in the models

Identification of two liquid-liquid phase transitions

Oscillatory behavior of thermal expansion as a signature

Abstract

The relation between liquid-liquid phase transitions and waterlike density anomalies in core-softened potentials of fluids was investigated in an exactly solvable one dimensional lattice model and a in a three dimensional fluid with fermi-like potential, the latter by molecular dynamics. Both systems were shown to present three liquid phases, two liquid-liquid phase transitions closely connected to two distinct regions of anomalous density increase. We propose that an oscillatory behavior observed on the thermal expansion coefficient as a function of pressure can be used as a signature of the connection between liquid-liquid phase and density.