Dear alps team i want ti rephrase my question to make it more precise I have fermion hubbard model 2 by 2 square plaquette total number of particle = 3 total spin S= 1/2 need ground state energy which will be plaquette momentum (Pi,0) and (0, Pi) degenerate The program I wrote is giving plaquette momentum (0,0) and (0,Pi) as ground state, which is wrong as seen in the paper. My statements are under. Please correct my statements. I tried very much but could not find the correct ground states. It is trivial task as written in paper. LATTICE_LIBRARY="/temp/ALPS/xml/lattices.xml"; MODEL_LIBRARY="/temp/ALPS/xml/models.xml"; MODEL="fermion Hubbard"; LATTICE="anisotropic square lattice"; L=2; W=2; Sz_total=0.5; U=0.5; CONSERVED_QUANTUMNUMBERS="N,Sz" N_total=3 { t=1.0;} Best Regards Khalid Loane