small fixes for density operators (#409)

Author: lkdvos

src/algorithms/toolbox.jl

@@ -199,7 +199,7 @@ function variance(
             state.AC[i], envs.GLs[i], H[i][:, :, :, end], envs.GRs[i][end]
         )
     end
-    lattice = physicalspace(state)
+    lattice = physicalspace(H)
     H_renormalized = InfiniteMPOHamiltonian(
         lattice, i => e * id(storagetype(eltype(H)), lattice[i]) for (i, e) in enumerate(e_local)
     )
@@ -226,7 +226,7 @@ function variance(state::InfiniteQP, H::InfiniteMPOHamiltonian, envs = environme
         GR = rightenv(envs, i, gs)
         return contract_mpo_expval(gs.AC[i], GL, H[i][:, :, :, end], GR[end])
     end
-    lattice = physicalspace(gs)
+    lattice = physicalspace(H)
     H_regularized = H - InfiniteMPOHamiltonian(
         lattice, i => e * id(storagetype(eltype(H)), lattice[i]) for (i, e) in enumerate(e_local)
     )

src/operators/mpohamiltonian.jl

@@ -442,6 +442,7 @@ function FiniteMPOHamiltonian(lattice::AbstractArray{<:VectorSpace}, local_opera
 
     # avoid using one(S)
     P = first(lattice)
+    P = P isa ProductSpace ? P[length(P)] : P
     _rightunit = rightunitspace(P)
     @assert _rightunit == leftunitspace(P) "only diagonal hamiltonians allowed"
 
@@ -530,6 +531,7 @@ function InfiniteMPOHamiltonian(lattice′::AbstractArray{<:VectorSpace}, local_
     )
     # avoid using one(S)
     P = first(lattice)
+    P = P isa ProductSpace ? P[length(P)] : P
     _rightunit = rightunitspace(P)
     @assert _rightunit == leftunitspace(P) "only diagonal hamiltonians allowed"