  We consider the low energy effective field model of graphene monolayer.
Coulomb interactions are taken into account. The model is simulated numerically
using the lattice discretization with staggered fermions. The two point
fermionic Green functions are calculated. We find that in the insulator phase
these Green functions almost do not depend on energy. This indicates that the
effective field model (in its insulator phase) does not correspond to the real
graphene.
