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 in a three-dimensional fluid with a 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 the liquid-liquid phase transition and density anomaly.

• Received 19 June 2012

DOI:https://doi.org/10.1103/PhysRevE.87.032303