  This paper presents an extended coarse-grained investigation of the elastic
properties of polystyrene. In particular, we employ the well-known MARTINI
force field and its modifications to perform extended molecular dynamics
simulations at the $\mu$s timescale, which take slow relaxation processes of
polystyrene into account, such that the simulations permit analyzing the bulk
modulus, the shear modulus, and the Poisson ratio. We show that through the
iterative modification of MARTINI force field parameters it turns out to be
possible to affect the shear modulus and the bulk modulus of the system, making
them closer to those values reported in the experiment.
