Diffusion anomaly in a three-dimensional lattice gas

Abstract

We investigate the relation between thermodynamic and dynamic properties of an associating lattice gas (ALG) model. The ALG combines a three dimensional lattice gas with particles interacting through a soft core potential and orientational degrees of freedom. From the competition between the directional attractive forces and the soft core potential results two liquid phases, double criticality and density anomaly. We study the mobility of the molecules in this model by calculating the diffusion constant at a constant temperature, D. We show that D has a maximum at a density ρ max and a minimum at a density ρ min < ρ max . Between these densities the diffusivity differs from the one expected for normal liquids. We also show that in the pressure-temperature phase-diagram the line of extrema in diffusivity is close to the liquid-liquid critical point and it is partially inside the temperature of maximum density (TMD) line.

Structure and anomalous solubility for hard spheres in an associating lattice gas model

“…26 Dynamic and thermodynamic properties of the system were previously obtained by Monte Carlo simulations 26,28,29 and analytical methods. 30 The model consists of a body centered cubic lattice where sites can be either occupied (σ i = 1) by a water molecule or empty (σ i = 0).…”

Dynamic transitions in a three dimensional associating lattice gas model

“…13 Here we address these questions by studying the associating lattice gas model that exhibits two liquid phases and different ordered phases. This waterlike model has density and diffusion anomalies 14,15 and its phase diagram has been investigated previously through Monte Carlo simulations 14 and cluster expansions. 16 In the numerical study of the model by Girardi et al 14,15 two coexisting liquid phases, as well as density and diffusion anomalies were found.…”

Lattice model for water-solute mixtures

“…Increasing µ a low density liquid phase (LDL) appears [32][33][34]38], where half of the sites of the lattice are occupied by particles (ρ * = 1/2). These sites are those belonging to one of the diamond sublattices [39] that can be defined on the BCC lattice.…”

“…In this work the water and the solute are modeled following the associating lattice gas model (ALG) [32][33][34] scheme. The two molecules are specified by adapting the hydrogen bond and the attractive interactions for each molecule.…”