The invited ALERT Special Lecture during the ALERT Workshop 2018 will be presented by Dr. Roland Pellenq, Director of Research at CNRS and MIT Senior Research Scientist. The envisaged title of his talk is: The potential of mean force: the tool to model dense colloidal systems. Find the abstract below.
We investigate the interactions responsible for the cohesion of strongly interacting colloidal materials such as clays, cement… It is known that the swelling/cohesive properties of these materials depend both on the nature of the some counter-ions compensating their surface charge along with the water intake. The overall goal of this work is to determine the right level of modeling complexity required to capture the behavior of these charged colloids immersed in an electrolyte and set up the stage for modeling at the meso-scale. From the (analytical) mean-field DLVO theory to a full atomistic description, we introduce the concept of “Potential of Mean Force” as the tool to get an efficient but still realistic description between strongly interacting colloidal grains such as clay and cement hydrate nanoparticles. In particular, we introduced the Explicit Solvent Primitive Model (ESPM), in which ions are modeled as charged hard spheres and solvent molecules as soft spheres with embedded point dipoles. We showed that taking explicitly into account the solvent in such a Primitive Model description, allows a quantitative description of system’s cohesion in quantitative agreement with atomistic scale results. From ionic correlation interactions to pure electrostatics, the ESPM approach is shown to be an efficient strategy to get a truly consistent multi-scale modeling approach of complex systems.