Hi,
The harmonic trap which I used in (the ALPS part of) the calculation of PRB82, 014202 (2010) (http://dx.doi.org/10.1103/PhysRevB.82.014202) are:
1. define "inhomogeneous chain lattice" as follows:
<LATTICEGRAPH name = "inhomogeneous open chain lattice"> <FINITELATTICE> <LATTICE ref="chain lattice"/> <EXTENT dimension="1" size ="L"/> <BOUNDARY type="open"/> </FINITELATTICE> <UNITCELL ref="simple1d"/> <INHOMOGENEOUS><VERTEX/></INHOMOGENEOUS> </LATTICEGRAPH>
2. add site-dependent 'mu' term in the parameter file:
LATTICE="inhomogeneous open chain lattice" MODEL="fermion Hubbard" CONSERVED_QUANTUMNUMBERS="Nup,Ndown" L=20 t=1 U=2 mu=-0.006*(x-L/2+0.5)^2 { Nup_total=10; Ndown_total=10 }
At least the above setting works fine for ALPS DMRG code. Of course you should check the convergence carefully by changing sweeps.
I don't think changing the model is necessary.
Best regards, -- Ryo IGARASHI, Ph.D. rigarash@issp.u-tokyo.ac.jp OpenPGP fingerprint: BAD9 71E3 28F3 8952 5640 6A53 EC79 A280 6A19 2319