  The perturbative renormalization of the Ginzburg-Landau model is reconsidered
based on the Feynman diagram technique. We derive renormalization group (RG)
flow equations, exactly calculating all vertices appearing in the perturbative
renormalization of the phi^4 model up to the epsilon^3 order of the
epsilon-expansion. In this case, the phi^2, phi^4, phi^6, and phi^8 vertices
appear. All these vertices are relevant. We have tested the expected basic
properties of the RG flow, such as the semigroup property. Under repeated RG
transformation R_s, appropriately represented RG flow on the critical surface
converges to certain s-independent fixed point. The Fourier-transformed
two-point correlation function G(k) has been considered. Although the
epsilon-expansion of X(k)=1/G(k) is well defined on the critical surface, we
have revealed an inconsistency of the perturbative method with the exact
rescaling of X(k), represented as an expansion in powers of k at k --> 0. We
have discussed also some aspects of the perturbative renormalization of the
two-point correlation function slightly above the critical point. Apart from
the epsilon-expansion, we have tested and briefly discussed also a modified
approach, where the phi^4 coupling constant u is the expansion parameter at a
fixed spatial dimensionality d.
