Thank you. I have indeed overlooked this important parameter.

It now works smoothly with spinless fermions or bosons. However for spinful fermions the time it takes is more than a thousand times (or more) longer. Even for tiny 2D systems the time it takes is huge. Is it a known limitation and is there a physical reason?

On Sat, Jul 8, 2017 at 2:48 AM, Michele Dolfi <dolfim@phys.ethz.ch> wrote:

Note that by default mps_evolve only works for nearest neighbors lattices.
In higher dimensions this is not the case, since the lattice is unrolled into a one dimensional chain with longer range interactions.

We have a second flavor of the time evolution algorithm for these cases, you can use it via the parameter:
te_type=mpo
Quite some improvements to this variant was introduced in ALPS 2.3, so I suggest you to use that version.

Best,
Michele