  We focus on finding a coarse grained description able to reproduce the
thermodynamic behavior of a molecular system by using mesoparticles
representing several molecules. Interactions between mesoparticles are modelled
by an interparticle potential, and an additional internal equation of state is
used to account for the thermic contribution of coarse grained internal degrees
of freedom. Moreover, as strong non-equilibrium situations over a wide range of
pressure and density are targeted, the internal compressibility of these
mesoparticles has to be considered. This is done by introducing a dependence of
the potential on the local environment of the mesoparticles, either by defining
a spherical local density or by means of a Voronoi tessellation. As an example,
a local density dependent potential is fitted to reproduce the Hugoniot curve
of a model of nitromethane, where each mesoparticle represents one thousand
molecules.
