  We compute the momentum dependence of the effective four quark interaction in
QCD after integrating out the gluons. Our method is based on a truncation of
exact renormalization group equations which should give reasonable results for
momenta above the confinement scale. The difference between the four quark
interaction and the heavy quark potential can be minimized for an optimal
renormalization scheme in Landau gauge. Within the momentum range relevant for
quarkonia our results agree with phenomenological potentials. We also calculate
the propagators for gluons and ghosts in Landau-gauge.
