  We study the renormalization of the Fermi velocity by the long-range Coulomb
interactions between the charge carriers in the Dirac-cone approximation for
the effective low-energy description of the electronic excitations in graphene
at half filling. Solving the coupled system of Dyson-Schwinger equations for
the dressing functions in the corresponding fermion propagator with various
approximations for the particle-hole polarization we observe that Fermi
velocity renormalization effects generally lead to a considerable increase of
the critical coupling for dynamical gap generation and charge-density wave
formation at the semimetal-insulator transition.
