  Using molecular dynamics simulations we investigate the finite-size
dependence of the dynamical properties of a diatomic supercooled liquid. The
simplicity of the molecule permits us to access the microsecond time scale. We
find that the relaxation time decreases simultaneously with the strength of
cooperative motions when the size of the system decreases. While the decrease
of the cooperative motions is in agreement with previous studies, the decrease
of the relaxation time opposes what has been reported to date in monatomic
glass formers and in silica. This result suggests the presence of different
competing physical mechanisms in the relaxation process. For very small box
sizes the relaxation times behavior reverses itself and increases strongly when
the box size decreases, thus leading to a nonmonotonic behavior. This result is
in qualitative agreement with defect and facilitation theories.
