Non-Equilibrium Molecular Dynamics Simulations: Techniques and Applications

摘要

These lectures notes are devoted to the presentation of properties of matter in non-equilibrium conditions by using the techniques of Non-Equilibrium Molecular Dynamics. As a first application, results on the simulation of shock waves in solids are presented. Shock propagation can be modeled by a direct Molecular Dynamics simulation. The shocked state is compared to a modeling through a dynamics constrained by the Hugoniot relations with a uniaxial compression: this new technique, named Hugoniotstat, allows to compute directly the shocked state properties without having to make a full study of the shock. The next application is concerned with properties of granular fluids. Those systems are always in a non equilibrium state with energy flowing from an external forcing towards the internal elastic energy of the grains. Constant-energy simulation of inelastic hard disks are performed by a rescaling of the velocities at every dissipative collisions, a method we call Sotostat. This technique is used to compare flow properties with predictions from continuum equations. Moreover the chaotic indicators of the system behavior, the Lyapunov spectrum, are computed and the influence of the dissipativity of the grains on the spectrum is discussed.