Dear All,
I'm currently using the ALPS DMRG algorithm to calculate energy eigenvalues for a given quantum model. After running many simulations and analyzing the results I have a few questions that I'm hoping you can answer.
1) The lattice model I'm looking at is an open ladder with 2-legs. Is the DMRG code supplied in ALPS capable of correctly handling such a lattice configuration?
2) I've also noticed that the results from these DMRG simulations are non-deterministic, that is the result is only consistent to a specific decimal point every run, given the same input parameters. Other DMRG programs I have used previously gave deterministic results given the same input parameters. I'm assuming that the inconsistency of the ALPS DMRG results is due to the utilization of the Lanczos algorithm to calculate the energy eigensets on each run. Can someone confirm that this is the case? Additionally, I have tried changing the 'LANCZOS_TOLERANCE' parameter, which I'm assuming would give better and more consistent results, but this has no effect on the results. Given that my assumption is correct what is the proper way to code this input parameter.
Thanks, Tyler Hewitt