  The blossoming of interest in colloids and nano-particles has given renewed
impulse to the study of hard-body systems. In particular, hard spheres have
become a real test system for theories and experiments. It is therefore
necessary to study the complex dynamics of such systems in presence of a
solvent; disregarding hydrodynamic interactions, the simplest model is the
Langevin equation. Unfortunately, standard algorithms for the numerical
integration of the Langevin equation require that interactions are slowly
varying during an integration timestep. This in not the case for hard-body
systems, where there is no clearcut between the correlation time of the noise
and the timescale of the interactions. Starting first from a splitting of the
Fokker-Plank operator associated with the Langevin dynamics, and then from an
approximation of the two-body Green's function, we introduce and test two new
algorithms for the simulation of the Langevin dynamics of hard-spheres.
