I'm trying to use DMRG to calculate the ground state of a Bose-Hubbard model. I created my own site type of spinless bosons and followed some DMRG examples to perform QN conserved DMRG with randomMPS with specific QN. It worked pretty well.
The problem happens when I saved the ground state psi in an hdf5 file and then tried to load this psi and use it as the initial state psi0 to run the same DMRG. However, I got the error saying the order of this tensor is greater than or equal to the ITensor order warning threshold 14. I made sure the maxlinkdim is 200 starting from the first sweep. It's a warning but it seems dmrg is not running as what I expected like with just randomMPS initial state.
is greater than or equal to the ITensor order warning threshold 14
I have two related questions:
Please see the discussion above. The key take-away of the discussion is that the same array of site indices used to originally make an MPS must be used to make a compatible MPO or other MPS. This array of site indices can be conveniently obtained from an existing MPS psi by calling:
sites = siteinds(psi)