Molecular Dynamics Study of Orientational Cooperativity in Water

Abstract

Recent experiments on liquid water show collective dipole orientation fluctuations dramatically slower then expected (with relaxation time $>$ 50 ns) [D. P. Shelton, Phys. Rev. B {\bf 72}, 020201(R) (2005)]. Molecular dynamics simulations of SPC/E water show large vortex-like structure of dipole field at ambient conditions surviving over 300 ps [J. Higo at al. PNAS, {\bf 98} 5961 (2001)]. Both results disagree with previous results on water dipoles in similar conditions, for which autocorrelation times are a few ps. Motivated by these recent results, we study the water dipole reorientation using molecular dynamics simulations in bulk SPC/E water for temperatures ranging from ambient 300 K down to the deep supercooled region of the phase diagram at 210 K. First, we calculate the dipole autocorrelation function and find that our simulations are well-described by a stretched exponential decay, from which we calculate the {\it orientational autocorrelation time} ${\tau }_a$. Second, we define a second characteristic time, namely the time required for the randomization of molecular dipole orientation, the {\it self-dipole randomization time} ${\tau }_r$, which is an upper limit on ${\tau }_a$; we find that ${\tau }_r\approx 5{\tau }_a$. Third, to check if there are correlated domains of dipoles in water which have large relaxation times compared to the individual dipoles, we calculate the randomization time ${\tau }_{\mathrm{box}}$ of the site-dipole field, the net dipole moment formed by a set of molecules belonging to a box of edge $L_{\mathrm{box}}$. We find that the {\it site-dipole randomization time} ${\tau }_{\mathrm{box}}\approx 2.5{\tau }_a$ for $L_{\mathrm{box}}\approx 3$Å, i.e. it is shorter than the same quantity calculated for the self-dipole. Finally, we find that the orientational correlation length is short even at low $T$.

arXiv comment25 Pages, 10 figures

References in corpus (16)

• Relation Between the Widom line and the Strong-Fragile Dynamic Crossover in Systems with a Liquid-Liquid Phase Transition
• Pressure Dependence of Fragile-to-Strong Transition and a Possible Second Critical Point in Supercooled Confined Water
• Dynamics of simulated water under pressure
• Thermodynamics, Structure, and Dynamics of Water Confined between Hydrophobic Plates
• Liquid-liquid phase transitions in supercooled water studied by computer simulations of various water models
• Dynamics of the rotational degrees of freedom in a supercooled liquid of diatomic molecules
• Supercooled confined water and the Mode Coupling crossover temperature
• Static and Dynamic Properties of Stretched Water
• Supercooled Water and the Kinetic Glass Transition II: Collective Dynamics
• Slow dynamics of water under pressure
• Idealized glass transitions for a system of dumbbell molecules
• Reorientational relaxation of a linear probe molecule in a simple glassy liquid
• Structural relaxation in a system of dumbbell molecules
• Precursor phenomena in frustrated systems
• A semi-schematic model for the center of mass dynamics in supercooled molecular liquids
• Test of the semischematic model for a liquid of linear molecules

Cited by in corpus (15)

• Water-like hierarchy of anomalies in a continuous spherical shouldered potential
• The origin of the Debye relaxation in liquid water and fitting the high frequency excess response
• Predictions of Dynamic Behavior Under Pressure for Two Scenarios to Explain Water Anomalies
• Finite-size scaling investigation of the liquid-liquid critical point in ST2 water and its stability with respect to crystallization
• Unravelling the contribution of local structures to the anomalies of water: the synergistic action of several factors
• Thermodynamic, Dynamic and Structural Anomalies for Shoulder-like potentials
• Cluster Monte Carlo and numerical mean field analysis for the water liquid--liquid phase transition
• Large Slowdown of Water Dynamics at Stacked Phospholipid Membranes for Increasing Hydration Level: All-Atoms Molecular Dynamics
• Characterizing the Hard and Soft Nanoparticle-Protein Corona with Multilayer Adsorption
• Liquid crystal phase and waterlike anomalies in a core-softened shoulder-dumbbells system
• Dynamically Slow Processes in Supercooled Water Confined Between Hydrophobic Plates
• Fluctuations of local electric field and dipole moments in water between metal walls
• Bottom-up derivation of an effective thermostat for united atoms simulations of water
• Influence of Surface Hydrophilicity and Hydration on the Rotational Relaxation of Supercooled Water on Graphene Oxide Surfaces
• Biological Effects of Microwaves: Thermal and nonThermal Mechanisms