Molecular Structure and Interaction in between Particles

For the description and modelling of particle systems, it is very important to understand inter-actions between particles and their origin. These interactions are based on physical-chemical processes in the contact area on a microscopic – atomic or molecular – level. Molecular simulations offer very good possibilities to examine basic physical-chemical processes in the contact area on an atomic level. They can give, e.g., the structure of wetting films or adsorbed molecule layers in the contact area or insight into the deformation of the particle surface. Moreover, it is possible to calculate from the simulation results the forces between the parti-cles as a mean force (MF) with respect to the particle distance. The MF is an average of the forces for all configurations of the molecules in the contact area at a given particle distance. It is an effective force between the particles. One can examine, e.g., systems with particles in a suspension, where the distance of two particles is decreased until contact and the liquid layers in between them are driven out. Similarly, one can examine the effect of deformations in the contact area of dry particle systems. These studies can be very helpful to derive normal force versus distance models for particle dynamics.