Cyrille Ibergay - Academia.edu (original) (raw)

Papers by Cyrille Ibergay

Research paper thumbnail of Calculation of the surface tension of n-alkanes using molecular simulations: operational expressions and long range corrections

Research paper thumbnail of Mesoscale Modeling of Polyelectrolyte Brushes with Salt

The Journal of Physical Chemistry B, 2010

We report dissipative particle dynamics (DPD) simulations of a polyelectrolyte brush under atherm... more We report dissipative particle dynamics (DPD) simulations of a polyelectrolyte brush under athermal solvent conditions. The electrostatic interactions are calculated using the particle-particle particle-mesh (PPPM) method with charges distributed over the particles. The polymer beads, counterions, co-ions, and solvent particles are modeled explicitly. The DPD simulations show a dependence of the brush height on the grafting density and the charge fraction that is typical of the nonlinear osmotic brush regime. We report the effect of the addition of salt on the structural properties of the brush. In the case of a polyelectrolyte brush with a high surface coverage, the simulations reproduce the transition between the nonlinear osmotic brush regime where the thickness of the brush is independent of the salt concentration and the salted regime where the brush height decreases weakly with the salt concentration.

Research paper thumbnail of Interaction between two polyelectrolyte brushes: a mesoscale modelling of the compression

Soft Matter, 2011

We report dissipative particle dynamics (DPD) simulations of two interacting polyelectrolyte brus... more We report dissipative particle dynamics (DPD) simulations of two interacting polyelectrolyte brushes under athermal solvent conditions. The standard DPD model is modified by the addition of the electrostatic interactions and of the spring-spring repulsion to model entangled ...

Research paper thumbnail of Molecular simulations of the n-alkane liquid-vapor interface: Interfacial properties and their long range corrections

Physical Review E, 2007

simulations have been performed to study the interfacial properties of the liquid-vapor interface... more simulations have been performed to study the interfacial properties of the liquid-vapor interface of alkanes. We highlight the chemical equilibrium of the liquid-vapor interface by calculating a local chemical potential including the appropriate long-range corrections profiles. We extend the "test-area" ͑TA͒ technique developed by Gloor et al. ͓J. Chem. Phys. 123, 134703 ͑2005͔͒ on Lennard-Jones and square-well fluids to molecular systems. We establish both operational expressions of the TA approach for the calculation of the surface tension profile and the corresponding long-range corrections by underlining the approximations used. We compare the results between the different operational expressions of the surface tension and focus on the truncation procedures to explain the difference between the different techniques using either the potential or force equations. We make the results of surface tension identical between the different methods by using consistent potential and force equations. In the case of a relatively small cutoff, we propose to show that the Irving-Kirkwood definition and TA methods lead to the same value of the surface tension under condition that appropriate long-range corrections be included in the calculation. We end this paper by calculation of the entropy change profile and a comparison with experiments.

Research paper thumbnail of Electrostatic Interactions in Dissipative Particle Dynamics: Toward a Mesoscale Modeling of the Polyelectrolyte Brushes

Journal of Chemical Theory and Computation, 2009

We report mesoscopic simulations of bulk electrolytes and polyelectrolyte brushes using the dissi... more We report mesoscopic simulations of bulk electrolytes and polyelectrolyte brushes using the dissipative particle dynamics (DPD) method. The calculation of the electrostatic interactions is carried out using both the Ewald summation method and the particle-particle particle-mesh technique with charges distributed over the particles. The local components of the pressure tensor are calculated using the Irving and Kirkwood, and the method of planes and mechanical equilibrium is demonstrated. The profiles of the normal component of the pressure tensor are shown to be similar for both the Ewald and particle-particle particle-mesh methods for a single polyelectrolyte brush. We show that the PPPM method with the MOP technique is the appropriate choice for simulations of this type. The mesoscale modeling of a strongly stretched polylectrolyte brush formed by strong charged polymer chains at a high grafting density shows that the polyelectrolyte follows the nonlinear osmotic regime, as expected from the calculation of the Gouy-Chapman length and the dimensionless Manning ratio.

Research paper thumbnail of Electrostatic Interactions in Dissipative Particle Dynamics: Toward a Mesoscale Modeling of the Polyelectrolyte Brushes

Journal of Chemical Theory …, 2009

We report mesoscopic simulations of bulk electrolytes and polyelectrolyte brushes using the dissi... more We report mesoscopic simulations of bulk electrolytes and polyelectrolyte brushes using the dissipative particle dynamics (DPD) method. The calculation of the electrostatic interactions is carried out using both the Ewald summation method and the particle−particle ...

Research paper thumbnail of Calculation of the surface tension of n-alkanes using molecular simulations: operational expressions and long range corrections

Research paper thumbnail of Mesoscale Modeling of Polyelectrolyte Brushes with Salt

The Journal of Physical Chemistry B, 2010

We report dissipative particle dynamics (DPD) simulations of a polyelectrolyte brush under atherm... more We report dissipative particle dynamics (DPD) simulations of a polyelectrolyte brush under athermal solvent conditions. The electrostatic interactions are calculated using the particle-particle particle-mesh (PPPM) method with charges distributed over the particles. The polymer beads, counterions, co-ions, and solvent particles are modeled explicitly. The DPD simulations show a dependence of the brush height on the grafting density and the charge fraction that is typical of the nonlinear osmotic brush regime. We report the effect of the addition of salt on the structural properties of the brush. In the case of a polyelectrolyte brush with a high surface coverage, the simulations reproduce the transition between the nonlinear osmotic brush regime where the thickness of the brush is independent of the salt concentration and the salted regime where the brush height decreases weakly with the salt concentration.

Research paper thumbnail of Interaction between two polyelectrolyte brushes: a mesoscale modelling of the compression

Soft Matter, 2011

We report dissipative particle dynamics (DPD) simulations of two interacting polyelectrolyte brus... more We report dissipative particle dynamics (DPD) simulations of two interacting polyelectrolyte brushes under athermal solvent conditions. The standard DPD model is modified by the addition of the electrostatic interactions and of the spring-spring repulsion to model entangled ...

Research paper thumbnail of Molecular simulations of the n-alkane liquid-vapor interface: Interfacial properties and their long range corrections

Physical Review E, 2007

simulations have been performed to study the interfacial properties of the liquid-vapor interface... more simulations have been performed to study the interfacial properties of the liquid-vapor interface of alkanes. We highlight the chemical equilibrium of the liquid-vapor interface by calculating a local chemical potential including the appropriate long-range corrections profiles. We extend the "test-area" ͑TA͒ technique developed by Gloor et al. ͓J. Chem. Phys. 123, 134703 ͑2005͔͒ on Lennard-Jones and square-well fluids to molecular systems. We establish both operational expressions of the TA approach for the calculation of the surface tension profile and the corresponding long-range corrections by underlining the approximations used. We compare the results between the different operational expressions of the surface tension and focus on the truncation procedures to explain the difference between the different techniques using either the potential or force equations. We make the results of surface tension identical between the different methods by using consistent potential and force equations. In the case of a relatively small cutoff, we propose to show that the Irving-Kirkwood definition and TA methods lead to the same value of the surface tension under condition that appropriate long-range corrections be included in the calculation. We end this paper by calculation of the entropy change profile and a comparison with experiments.

Research paper thumbnail of Electrostatic Interactions in Dissipative Particle Dynamics: Toward a Mesoscale Modeling of the Polyelectrolyte Brushes

Journal of Chemical Theory and Computation, 2009

We report mesoscopic simulations of bulk electrolytes and polyelectrolyte brushes using the dissi... more We report mesoscopic simulations of bulk electrolytes and polyelectrolyte brushes using the dissipative particle dynamics (DPD) method. The calculation of the electrostatic interactions is carried out using both the Ewald summation method and the particle-particle particle-mesh technique with charges distributed over the particles. The local components of the pressure tensor are calculated using the Irving and Kirkwood, and the method of planes and mechanical equilibrium is demonstrated. The profiles of the normal component of the pressure tensor are shown to be similar for both the Ewald and particle-particle particle-mesh methods for a single polyelectrolyte brush. We show that the PPPM method with the MOP technique is the appropriate choice for simulations of this type. The mesoscale modeling of a strongly stretched polylectrolyte brush formed by strong charged polymer chains at a high grafting density shows that the polyelectrolyte follows the nonlinear osmotic regime, as expected from the calculation of the Gouy-Chapman length and the dimensionless Manning ratio.

Research paper thumbnail of Electrostatic Interactions in Dissipative Particle Dynamics: Toward a Mesoscale Modeling of the Polyelectrolyte Brushes

Journal of Chemical Theory …, 2009

We report mesoscopic simulations of bulk electrolytes and polyelectrolyte brushes using the dissi... more We report mesoscopic simulations of bulk electrolytes and polyelectrolyte brushes using the dissipative particle dynamics (DPD) method. The calculation of the electrostatic interactions is carried out using both the Ewald summation method and the particle−particle ...