  Based on the linear response of the fermion propagator with respect to an
external field, we first derive a model-independent expression for the
staggered spin susceptibility in which the influence of the full pseudoscalar
vertex function is included. This expression for the staggered spin
susceptibility is quite different from that given in the previous literature.
The numerical values of the staggered spin susceptibility are calculated within
the framework of the Dyson-Schwinger approach. Our numerical result shows that
the nonperturbative dressing effects on the fermion propagator is very
important when one studies the staggered spin susceptibility which
corresponding to antiferromagnetic correlation in both Nambu phase and Winger
phase.
