  We have computed the global quantum discord and von Neumann entropy of
multipartite two-level atomic systems interacting with a single-mode Fock
field. We use Tavis-Cumming model. We have explored how quantum correlations
and quantum entanglement evolve with time in such systems. The quantum system
is prepared initially in a mixed state and different parameters are varied to
see how they affect the information processing in the system. The dynamical
character of the global quantum discord and von Neumann entropy show an
interplay between classical and non-classical correlations. Photons in this
model play an important role to assist the global quantum discord and von
Neumann entropy and we observed that the effects of the field on the global
quantum discord and von Neumann entropy reside in the time evolution of the
system indicating that both atom and field states have become entangled. The
global quantum discord is assisted in a non-linear fashion with the number of
photons in the system. The global quantum discord and von Neumann entropy show
linear behavior with each other in the dynamics of the system. The effects of
intrinsic decoherence on the dynamics of the global quantum discord and von
Neumann entropy are also studied. We have extrapolated the results for a large
photon number on the system. We have studied the effect of the change in the
size of the system on the maximum value of global quantum discord and von
Neumann entropy and we have estimated the scaling coefficients for this
behavior.
