Diffusion Anomaly in an Associating Lattice Gas Model

Abstract

We investigate the relation between thermodynamic and dynamic properties of an associating lattice gas (ALG) model. The ALG combines a two 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 ${\rho }_{max}$ and a minimum at a density ${\rho }_{min}<{\rho }_{max}$. 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 inside the temperature of maximum density (TMD) line.

12 pages, 9 figures

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Cited by in corpus (8)

• Anomalous structure and dynamics of the Gaussian-core fluid
• Generalized Rosenfeld scalings for tracer diffusivities in not-so-simple fluids: Mixtures and soft particles
• Structural anomalies of fluids: Origins in second and higher coordination shells
• Solution of an associating lattice gas model with density anomaly on a Husimi lattice
• Dynamic Transitions in a Two Dimensional Associating Lattice Gas Model
• Diffusion anomaly and dynamic transitions in the Bell-Lavis water model
• Thermodynamic and dynamic anomalies in a one dimensional lattice model of liquid water
• Residual entropy and waterlike anomalies in the repulsive one dimensional lattice gas