  The global density of states (GDOS) close to the band center $\epsilon=0$ for
a particle hopping on a square lattice and subjected to disorder that preserves
the bipartite symmetry of the lattice is computed using field theoretical
methods. The GDOS diverges like $ |\epsilon|^{-1}\exp (-c|\ln\epsilon|^{\kappa}
) $ with $\kappa=2/3$ in agreement with a prediction by Motrunich \textit{et
al.} and in disagreement with an older prediction by Gade ($\kappa=1/2$).
