I have posted these messages. They have no answers. Please take some time to answer them as I am student and answers from your part are very important to me. I am waiting Dear alps team, I am reproducing the spectrum on page 3 of this paper, which is the Lowest spectrum of the hubbard model on a plaquette. Eigenstates are labelled by total spin S and plaquette momentum Qx,Qy = 0, ?. author = "Ehud Altman and Assa Auerbach", title = "Plaquette Boson -- Fermion Model of Cuprates", condmat = "cond-mat/0108087", I have written the following program 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 U=1000000000 CONSERVED_QUANTUMNUMBERS="N,Sz" {N_total=3; Sz_total=0.5; t=1.0;} {N_total=3; Sz_total=1.5; t=1.0;} my results with fulldiag are not matching with the paper. Probably I am not mentiong the total_spin total_particle or conserved quantum number properly. i recognize 0 holes as 4 particles, 1 holes as 3 particles and 2 holes as 2 particles in 2 by 2 pluquette. Please take some time to correct me. Best Regards Khalid loane ------------------------------ Message: 3 Date: Thu, 16 Apr 2009 11:55:03 -0700 (PDT) From: khalid hassan <mkhloane@yahoo.com> Subject: [ALPS-users] repharasing the lowest spectrum fermion hubbard question To: alps users alps users <comp-phys-alps-users@phys.ethz.ch> Message-ID: <178183.68074.qm@web59405.mail.ac4.yahoo.com> Content-Type: text/plain; charset=us-ascii 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 Dear alps team, I am reproducing the spectrum on page 3 of this paper, which is the Lowest spectrum of the hubbard model on a plaquette. Eigenstates are labelled by total spin S and plaquette momentum Qx,Qy = 0, ?. author = "Ehud Altman and Assa Auerbach", title = "Plaquette Boson -- Fermion Model of Cuprates", condmat = "cond-mat/0108087", I have written the following program 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 U=1000000000 CONSERVED_QUANTUMNUMBERS="N,Sz" {N_total=3; Sz_total=0.5; t=1.0;} {N_total=3; Sz_total=1.5; t=1.0;} my results with fulldiag are not matching with the paper. Probably I am not mentiong the total_spin total_particle or conserved quantum number properly. i recognize 0 holes as 4 particles, 1 holes as 3 particles and 2 holes as 2 particles in 2 by 2 pluquette. Please take some time to correct me. Best Regards Khalid loane