Colloidal spheres with a partial platinum surface coating perform auto-phoretic motion when suspe... more Colloidal spheres with a partial platinum surface coating perform auto-phoretic motion when suspended in hydrogen peroxide solution. We present a theoretical analysis of the self-propulsion velocity of these particles using a continuum multi-component, self-diffusiophoretic model. With this model as a basis, we show how the slip-layer approximation can be derived and in which limits it holds. First, we consider the differences between the full multi-component model and the sliplayer approximation. Then the slip model is used to demonstrate and explore the sensitive nature of the particle's velocity on the details of the molecule-surface interaction. We find a strong asymmetry in the dependence of the colloid's velocity as a function of the level of catalytic coating, when there is a different interaction between the solute and solvent molecules and the inert and catalytic part of the colloid, respectively. The direction of motion can even be reversed by varying the level of ...
We introduce a novel method to couple Lennard-Jones beads to a lattice-Boltzmann fluid by adding ... more We introduce a novel method to couple Lennard-Jones beads to a lattice-Boltzmann fluid by adding a term which represents the slip within the Debye layer with respect to the surrounding fluid. The method produces realistic electrophoretic dynamics of charged free chains, as well as the correct stall force in the limit of a thin Debye layer. Our simulations also demonstrate how a net-neutral polyampholyte can have a nonzero net force due to hydrodynamic interactions. This method represents an efficient way to simulate a wide variety of complex problems in electrohydrodynamics.
We propose a self-consistent geometry optimized cell model approach to study osmotic properties o... more We propose a self-consistent geometry optimized cell model approach to study osmotic properties of stiff-chain polyelectrolyte solutions. In contrast with the usual monotonic Poisson-Boltzmann prediction, the cell model predicts the correct nonmonotonic dependence of the osmotic coefficient on concentration. A lower degree of polymerization is found to reduce significantly the counterion condensation in a typical dilute strong polyelectrolyte. The results agree quantitatively with simulations of a corresponding many-body bulk system up to a dense semidilute regime.
Most of the force fields for ionic liquids cannot properly describe statics and dynamics. In this... more Most of the force fields for ionic liquids cannot properly describe statics and dynamics. In this context, we propose an efficient method to adapt force fields, the basis of any classical molecular dynamics simulation. In the parameterisation process, a target function is minimized by a conjugate gradient based approach that vastly accelerates the tuning of the force field parameters through parallelization. As the description of the dynamics is captured in the parameterisation of the partial charges, we fit the short range parameters using only static properties, thus avoiding long simulations for the force field refinement. In the validation of the final parameterisation, the force field gives a good description of the dynamics in terms of the conductivity, especially in the temperature regime where the reference properties are matched very accurately. This method is sufficiently general and easily altered to fit an arbitrary set of reference properties, such that it can be considered for the construction of a versatile, transferable force field for ionic liquids.
... American Chemical Society. E-mail: gary.slater@uOttawa.ca. ... the tube. The Bjerrum length w... more ... American Chemical Society. E-mail: gary.slater@uOttawa.ca. ... the tube. The Bjerrum length was set to 2σ MD , an appropriate value for water.(8) Wall beads experience a harmonic potential about a point on an FCC lattice. Note ...
... Email: {limbach, holm, kremer}@mpip-mainz.mpg.de Summary: Using extensive Molecular Dynamics ... more ... Email: {limbach, holm, kremer}@mpip-mainz.mpg.de Summary: Using extensive Molecular Dynamics (MD) simulations we study the behavior of polyelectrolytes in poor solvents, where we take explicitely care of the counterions. The resulting pearl-necklace structures are ...
Colloidal spheres with a partial platinum surface coating perform auto-phoretic motion when suspe... more Colloidal spheres with a partial platinum surface coating perform auto-phoretic motion when suspended in hydrogen peroxide solution. We present a theoretical analysis of the self-propulsion velocity of these particles using a continuum multi-component, self-diffusiophoretic model. With this model as a basis, we show how the slip-layer approximation can be derived and in which limits it holds. First, we consider the differences between the full multi-component model and the sliplayer approximation. Then the slip model is used to demonstrate and explore the sensitive nature of the particle's velocity on the details of the molecule-surface interaction. We find a strong asymmetry in the dependence of the colloid's velocity as a function of the level of catalytic coating, when there is a different interaction between the solute and solvent molecules and the inert and catalytic part of the colloid, respectively. The direction of motion can even be reversed by varying the level of ...
We introduce a novel method to couple Lennard-Jones beads to a lattice-Boltzmann fluid by adding ... more We introduce a novel method to couple Lennard-Jones beads to a lattice-Boltzmann fluid by adding a term which represents the slip within the Debye layer with respect to the surrounding fluid. The method produces realistic electrophoretic dynamics of charged free chains, as well as the correct stall force in the limit of a thin Debye layer. Our simulations also demonstrate how a net-neutral polyampholyte can have a nonzero net force due to hydrodynamic interactions. This method represents an efficient way to simulate a wide variety of complex problems in electrohydrodynamics.
We propose a self-consistent geometry optimized cell model approach to study osmotic properties o... more We propose a self-consistent geometry optimized cell model approach to study osmotic properties of stiff-chain polyelectrolyte solutions. In contrast with the usual monotonic Poisson-Boltzmann prediction, the cell model predicts the correct nonmonotonic dependence of the osmotic coefficient on concentration. A lower degree of polymerization is found to reduce significantly the counterion condensation in a typical dilute strong polyelectrolyte. The results agree quantitatively with simulations of a corresponding many-body bulk system up to a dense semidilute regime.
Most of the force fields for ionic liquids cannot properly describe statics and dynamics. In this... more Most of the force fields for ionic liquids cannot properly describe statics and dynamics. In this context, we propose an efficient method to adapt force fields, the basis of any classical molecular dynamics simulation. In the parameterisation process, a target function is minimized by a conjugate gradient based approach that vastly accelerates the tuning of the force field parameters through parallelization. As the description of the dynamics is captured in the parameterisation of the partial charges, we fit the short range parameters using only static properties, thus avoiding long simulations for the force field refinement. In the validation of the final parameterisation, the force field gives a good description of the dynamics in terms of the conductivity, especially in the temperature regime where the reference properties are matched very accurately. This method is sufficiently general and easily altered to fit an arbitrary set of reference properties, such that it can be considered for the construction of a versatile, transferable force field for ionic liquids.
... American Chemical Society. E-mail: gary.slater@uOttawa.ca. ... the tube. The Bjerrum length w... more ... American Chemical Society. E-mail: gary.slater@uOttawa.ca. ... the tube. The Bjerrum length was set to 2σ MD , an appropriate value for water.(8) Wall beads experience a harmonic potential about a point on an FCC lattice. Note ...
... Email: {limbach, holm, kremer}@mpip-mainz.mpg.de Summary: Using extensive Molecular Dynamics ... more ... Email: {limbach, holm, kremer}@mpip-mainz.mpg.de Summary: Using extensive Molecular Dynamics (MD) simulations we study the behavior of polyelectrolytes in poor solvents, where we take explicitely care of the counterions. The resulting pearl-necklace structures are ...
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