Hi,

I am using itensor v3 to compute ground state of (H-E)^2=H^2-2EH+E^2, where H is Fermi Hubbard Hamiltonian as defined in http://itensor.org/docs.cgi?page=classes/autompo&vers=cppv3 except I am calculating it in 2D square lattice and E is some constant. In order to construct H^2 I used nmultMPO function flowing way:

auto H = toMPO(ampo);

auto Hn = toMPO(ampo);

auto HH = MPO{};

nmultMPO(prime(H),Hn,HH,{"MaxDim",1000,"Cutoff",1E-14});

so constructed HH (i.e. H^2) works fine with operation like inner(psi,HH,psi) but calling it upon dmrg function returns following message:

dim(inds(phi.front())) = 16

A.size() = 64

From line 137, file /data/pn1_1/psharma/ITensor-v3/itensor/iterativesolvers.h

davidson: size of initial vector should match linear matrix size

davidson: size of initial vector should match linear matrix size

Aborted (core dumped)

while dmrg function works perfectly fine with H and same initial MPS (used for HH).

Is there a way to fix this issue or do there exist any other simple way to find ground state of my problem?