  We investigate the correlations between different bipartitions of an exactly
solvable one-dimensional many-body Moshinsky model consisting of Nn "nuclei"
and Ne "electrons". We study the dependence of entanglement on the
inter-particle interaction strength, on the number of particles, and on the
particle masses. Consistent with kinematic intuition, the entanglement between
two subsystems vanishes when the subsystems have very different masses, while
it attains its maximal value for subsystems of comparable mass. We show how
this entanglement feature can be inferred by means of the Born-Oppenheimer
Ansatz, whose validity and breakdown can be understood from a quantum
information point of view.
