1-D Hubbard Chain(N=8), ground state energy

hoss2490

Greetings,
I am trying to track down some exact diagonalization results (specifically, ground state energies...just trying to check the ED code) for 1-D Hubbard chains with nearest neighbor hopping and weak coupling (no chemical potential). (t=1, U=0, 4-8 sites, half-filling)
Also, any suggestions on how to reduce the Hilbert space (besides working in the Sz=0 sub-space) would be appreciated.
Point me to a good reference and I will be thankful.