Constant energy MD simulation of a water molecule (TIP4P water model) between Cl- (yellow) and Na+ (cyan). The ions are tethered to their initial position by a harmonic spring.
The first movie shows every single time step (dt = 1fs) that has been calculated by integrating Newton's equations of motions of the particles. Total simulated time of the movie: 5 ps.
The second movie is more representative of what one normally sees of a MD simulation: Only every 1 ps is saved and visualised. Total time of the simulation is 50 ps (i.e. 50 frames).