scholarly journals Sub-diffusion and population dynamics of water confined in soft environments

Nanoscale ◽  
2016 ◽  
Vol 8 (6) ◽  
pp. 3314-3325 ◽  
Author(s):  
Samuel Hanot ◽  
Sandrine Lyonnard ◽  
Stefano Mossa
Keyword(s):  
Molecular Dynamics ◽  
Population Dynamics ◽  
Molecular Dynamics Simulations ◽  
Ionic Surfactants ◽  
Water Molecules ◽  
Matrix Interface ◽  
Diffusive Behavior ◽  
Water Matrix ◽  
Depth Analysis ◽  
Dynamics Simulations

By molecular dynamics simulations, we show that dynamics of water confined in ionic surfactants soft confining matrices is sub-diffusive. Our in-depth analysis reveals that this sub-diffusive behavior originates at the water–matrix interface, where water molecules can be trapped for extended periods of time.

Anomalous diffusion of water molecules at grain boundaries in ice Ih

2018 ◽  
Vol 20 (20) ◽  
pp. 13944-13951 ◽  
Author(s):  
Pedro Augusto Franco Pinheiro Moreira ◽  
Roberto Gomes de Aguiar Veiga ◽  
Ingrid de Almeida Ribeiro ◽  
Rodrigo Freitas ◽  
Julian Helfferich ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Grain Boundaries ◽  
Anomalous Diffusion ◽  
First Principles ◽  
Water Molecules ◽  
Diffusive Behavior ◽  
Classical Molecular Dynamics ◽  
Dynamics Simulations

First-principles and classical molecular dynamics simulations show that diffusion of water molecules at pre-melted grain boundaries in ice is glassy-like, showing sub-diffusive behavior.

scholarly journals Origin and control of ionic hydration patterns in nanopores

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Miraslau L. Barabash ◽  
William A. T. Gibby ◽  
Carlo Guardiani ◽  
Alex Smolyanitsky ◽  
Dmitry G. Luchinsky ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Distribution Functions ◽  
Water Molecules ◽  
Surrounding Water ◽  
Ionic Hydration ◽  
Hydration Shells ◽  
Water Layers ◽  
Dynamics Simulations ◽  
And Control

AbstractIn order to permeate a nanopore, an ion must overcome a dehydration energy barrier caused by the redistribution of surrounding water molecules. The redistribution is inhomogeneous, anisotropic and strongly position-dependent, resulting in complex patterns that are routinely observed in molecular dynamics simulations. Here, we study the physical origin of these patterns and of how they can be predicted and controlled. We introduce an analytic model able to predict the patterns in a graphene nanopore in terms of experimentally accessible radial distribution functions, giving results that agree well with molecular dynamics simulations. The patterns are attributable to a complex interplay of ionic hydration shells with water layers adjacent to the graphene membrane and with the hydration cloud of the nanopore rim atoms, and we discuss ways of controlling them. Our findings pave the way to designing required transport properties into nanoionic devices by optimising the structure of the hydration patterns.

scholarly journals Positively and Negatively Hydrated Counterions in Molecular Dynamics Simulations of DNA Double Helix

2020 ◽  
Vol 65 (6) ◽  
pp. 510
Author(s):  
S. Perepelytsya
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Double Helix ◽  
Dipole Moments ◽  
Hydration Shell ◽  
Minor Groove ◽  
Water Molecules ◽  
Negative Hydration ◽  
Dynamics Simulations ◽  
Dna Double Helix

The DNA double helix is a polyanionic macromolecule that is neutralized in water solutions by metal ions (counterions). The property of counterions to stabilize the water network (positive hydration) or to make it friable (negative hydration) is important in terms of the physical mechanisms of stabilization of the DNA double helix. In the present research, the effects of positive hydration of Na+ counterions and negative hydration of K+ and Cs+ counterions incorporated into the hydration shell of the DNA double helix have been studied using molecular dynamics simulations. The results have shown that the dynamics of the hydration shell of counterions depends on the region of the double helix: minor groove, major groove, and outside the macromolecule. The longest average residence time has been observed for water molecules contacting with the counterions localized in the minor groove of the double helix (about 50 ps for Na+ and lower than 10 ps for K+ and Cs+). The estimated potentials of the mean force for the hydration shells of counterions show that the water molecules are constrained too strongly, and the effect of negative hydration for K+ and Cs+ counterions has not been observed in the simulations. The analysis has shown that the effects of counterion hydration can be described more accurately with water models having lower dipole moments.

scholarly journals Self-assembly and adsorption of cetyltrimethylammonium bromide and didodecyldimethylammonium bromide surfactants at the mica–water interface

Soft Matter ◽  
2019 ◽  
Vol 15 (41) ◽  
pp. 8402-8411 ◽  
Author(s):  
Georgia Tsagkaropoulou ◽  
Finian J. Allen ◽  
Stuart M. Clarke ◽  
Philip J. Camp
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Self Assembly ◽  
Cetyltrimethylammonium Bromide ◽  
Ionic Surfactants ◽  
Water Interface ◽  
Didodecyldimethylammonium Bromide ◽  
Dynamics Simulations ◽  
Shed Light

Molecular-dynamics simulations are used to explore bilayers formed by simple ionic surfactants at the mica–water interface, and to shed light on experimental observations.

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