Diffusion anomaly in a cell model for water

de los Santos, F.¹ and Franzese, G.¹

¹Department of "Electromagnetismo y Física de la Materia", Universidad de Granada, Spain

Liquid water shows many unique and unusual properties and several scenarios have been proposed to interpret them: liquid-liquid critical point, singularity free, etc. Here, we present a simple Hamiltonian model that reproduces the basic properties of liquid water and covers various of these scenarios by a simple, physically motivated one-parameter tuning. In particular, it enables to distinguish between the singularity free scenario and the liquid-liquid critical point scenarios. Extensive Monte Carlo simulations of this model account for the density anomaly, the crossover from Arrhenius to non-Arrhenius behavior upon increasing pressure, the (recently observed in experiments) density minimum at low temperature, and the diffusivity anomaly. The two latter are independent from the existence of a 2nd critical point.