Density anomaly in a minimum model of water-alcohol mixtures

Abstract

We study the change in the temperature of maximum density (TMD) of a waterlike solvent when small amounts of solute are added to the mixture. The water is modeled as a two length scales potential, which is known to exhibit waterlike characteristic anomalies, while the solute is chosen to have an attractive interaction with the solvent. If the solute is a structure maker the TMD increases with the addition of solute, while if it is a structure breaker the TMD decreases.Both in an exact one dimensional model and using molecular dynamics in three dimensions we show that the necessary ingredient to represent structure makers is a strong solute-solvent attraction.