Dear ITensor developers:

I am consider about the time evolution of electron wave packet in interacting model. First I got the ground state using static DMRG, the electron packet for example,

$$

h^{\dagger}\left(k*{0}\right)=\sum_{j} a_{j} e^{i k*{0} j} c^{\dagger}_{j}

$$

then I try to use the AutoMPO, toMPO, and applyMPO get the excited state $\left|\Psi*{e}\right\rangle=h^{\dagger}\left(k*{0}\right)\left|\Psi_{0}\right\rangle$, but the ITENSOR give me the errors

I = (dim=2|id=932|"l=39,Link")

1: 2 QN()

Q = QN({"Nf",1,-1},{"Sz",1})

From line 683, file index.cc

Index does not contain given QN block.

the minimal code is:

auto [energy, psi] = dmrg(H, psi0, sweeps);

auto AmpoTemp = AutoMPO(sites);// Hubbard Model

for (auto b : range1(int(N)))

{

AmpoTemp += Coefficent, "Cup", b;

}

auto Htemp=toMPO(AmpoTemp);

auto NewPsi=applyMPO(Htemp,psi,{"Method=","DensityMatrix","MaxDim=",1000,"Cutoff=",1E-8});// |y>=h|x>

NewPsi.noPrime().normalize();

If I change the Cup to Nup, it works. I want to know why and how to fix it. Many thanks!