N_total is not a quantum number, but N is the quantum number. Have you tried specifying CONSERVED_QUANTUMNUMBERS="N"?

On Mar 27, 2013, at 10:06 AM, Jakub Zakrzewski <jakub.zakrzewski@gmail.com> wrote:

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

--
Jakub Zakrzewski
Zakład Optyki Atomowej
Instytut Fizyki im. M. Smoluchowskiego
ul. Reymonta 4, 30-059 Kraków, Poland
+48-12-6635555, fax +48126338494
http://chaos.if.uj.edu.pl/~kuba