  We present the results of the Monte-Carlo simulation of graphene-like
statistical model in terms of occupation numbers. We study the problem of the
phase transition in graphene to an insulating phase. Only antiferromagnetic
order parameter was studied at the moment by means of Hybrid Monte-Carlo
process on the hexagonal lattice because of the sign problem for excitonic
order parameter in fermionic determinant. Therefore we have studied the
possibility of the phase transition to an excitonic phase by means of
simplified Monte-Carlo process on the hexagonal lattice. We show that this
phase, which corresponds to a charge polarization of graphene sublattices, can
appear at some values of Coulomb electron-electron potentials. In this work we
study the dependence of the phase transition characteristics on the strength of
on-site electron-electron interaction. We show that excitonic phase transition
is also impossible in suspended graphene.
