On Dec 3, 2010, at 5:56 AM, Chong You Quan wrote:

Hi,

I had previously posted some questions and I appreciate the previous reply from Matthias Troyer.
I'm using ALPS 1.3.5 on Linux currently. I'm still learning about ALPS and DMRG and I'd just like to clarify a few more questions:
1. Is it possible to get the ground state wavefunction using the simple DMRG application for a heisenberg spin chain? As far as I know, a spin model needs to be specified but for the simple DMRG it is non-interacting.. But I don't get the relationship to specification of a model.

SImple DMRG is for a particle in a box and not a many body problem.

2. Is it possible to get the ground state wavefunction using the full DMRG application? I am thinking of reconstructing the wavefunction from the truncated density matrix. As far as I have seen in the code, the truncation of the wavefunction is done by first reordering the basis, then resizing the vector. Am I right on this? If so, is there any way which I could reconstruct the wavefunction in the original basis of the spins of a heisenberg spin chain?

yes, you could in principle but that needs exponential memory and is unfeasible. Why do you need the wave function? Are expectation values of operators not enough?

Matthias