[ALPS-users] What am I doing wrong?

Hello everybody,

Let us take such a simple input file with irrelevant name parbh:

LATTICE="open chain lattice" MODEL="boson Hubbard" L=8 Nmax=4 N_total=8 NONLOCAL=0 U = 1.0 t = 0.24 CONSERVED_QUANTUMNUMBERS="N_total" SWEEPS=8 NUMBER_EIGENVALUES=1 {MAXSTATES=100}

I produce parbh.in.xml and then I run sparsediag getting a proper ground state energy (checked independently outside alps)

-1.457060131536948

I use DMRG on the same input file obtaining LOWER eigenenergy...

-1.6132399980266807 the result is little dependent on SWEEPS. MAXSTATES (which are rather large) and is obviously incorrect.

I must be doing something wrong but what is it? Help welcome

Thanks in advance, kuba