  The $T=0$ spin stiffness $\rho _{s}$ and the transverse susceptibility $\chi
_{\perp }$ of the square lattice half-filled Hubbard model are calculated as a
function of the Hubbard parameter ratio $U/t$ by series expansions around the
Ising limit. We find that the calculated spin-stiffness, transverse
susceptibility, and sublattice magnetization for the Hubbard model smoothly
approach the Heisenberg values for large $U/t$. The results are compared for
different $U/t$ with RPA and other numerical studies.
