Diffusion anomaly and dynamic transitions in the Bell–Lavis water model

Abstract

A molecular dynamics investigation of the structural and dynamic properties of the ionic liquid 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide J. Chem. Phys. 135, 124507 (2011) Dynamics of thermal diffusion in a linear temperature field J. Appl. Phys. 110, 044908 (2011) Soret motion in non-ionic binary molecular mixtures J. Chem. Phys. 135, 054102 (2011) On the coupling between slow diffusion transport and barrier crossing in nucleation J. Chem. Phys In this paper we investigate the dynamic properties of the minimal Bell-Lavis ͑BL͒ water model and their relation to the thermodynamic anomalies. The BL model is defined on a triangular lattice in which water molecules are represented by particles with three symmetric bonding arms interacting through van der Waals and hydrogen bonds. We have studied the model diffusivity in different regions of the phase diagram through Monte Carlo simulations. Our results show that the model displays a region of anomalous diffusion which lies inside the region of anomalous density, englobed by the line of temperatures of maximum density. Further, we have found that the diffusivity undergoes a dynamic transition which may be classified as fragile-to-strong transition at the critical line only at low pressures. At higher densities, no dynamic transition is seen on crossing the critical line. Thus evidence from this study is that relation of dynamic transitions to criticality may be discarded.

Closed-loop liquid-vapor equilibrium in a one-component system

“…In order to investigate this issue, we have found it convenient to analyze a simple lattice model whose results are expected to be representative of what can be found for models in the continuum [11,17]. The computation of phase diagrams is usually much cheaper in terms of CPU time for lattice models, which, in spite of their simplicity, can often capture the essential features of the phase diagrams of associating molecules and network fluids [11,[17][18][19][20][21][22][23][24][25].…”

Hydration and anomalous solubility of the Bell-Lavis model as solvent

“…However, for finite temperatures, the transition between the two liquids becomes critical, as shown from detailed systematic analysis of simulational data [25]. The two liquid phases do not coexist and the density varies continuously at the phase transition as shown by susceptibility measurements on sublattice density fluctuations [27]. In order to stress the absence of a density gap we denominate the two liquid phases as structured (SL) and nonstructured liquid (NSL), instead of adopting the usual low-density liquid (LDL) and high-density liquid (HDL) nomenclature.…”

“…Both models present several of the anomalous features of water [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. However, the second kind of model does not involve specific orientation of low-energy pairs of particles: pair energy is controlled by distance, not by orientation.…”

“…Our approach is that of a minimal statistical model. We consider a two-dimensional lattice model proposed originally by Bell and Lavis [7] and shown by us [25,27] to exhibit many anomalous properties despite the absence of liquid polymorphism. In this study we add noninteracting solute particles which occupy a single lattice site in order to investigate the effect of solute on solvent properties as well as the effect of solute solubility.…”

Residual entropy and waterlike anomalies in the repulsive one dimensional lattice gas

“…In this direction, both thermodynamics [5][6][7][8][9][10] and kinetics [11,12] where investigated in lattice models with waterlike behavior. Nevertheless, approximations employed in two and three dimensions(3D), and even some exact solutions in one dimension (1D), tend to generate complex sets of equations whose analyses is often performed numerically.…”