Update evolve code

src/Ansatz/Chain.jl

@@ -652,24 +652,27 @@ function unpack_2sitewf!(ψ::Chain, bond, left_inds, right_inds, virtualind)
     return ψ
 end
 
+evolve(ψ::Chain, mpo::Chain) = evolve!(copy(ψ), mpo)
+
 """
     evolve!(ψ::Chain, mpo::Chain)
 
 Applies a Matrix Product Operator (MPO) `mpo` to the [`Chain`](@ref).
 """
-function evolve(ψ::Chain, mpo::Chain)
+function evolve!(ψ::Chain, mpo::Chain)
     updated_tensors = Tensor[]
     Λ = Tensor[]
     L = nsites(ψ)
 
     for i in 1:L
-        t = contract(select(ψ, :tensor, Site(i)), select(mpo, :tensor, Site(i)); dims = (select(ψ, :index, Site(i)),))
+        contractedind = select(ψ, :index, Site(i))
+        t = contract(select(ψ, :tensor, Site(i)), select(mpo, :tensor, Site(i)); dims = (contractedind,))
         physicalind = select(mpo, :index, Site(i))
 
         # Fuse the two right legs of t into one
         if i == 1
             wanted_inds = (physicalind, rightindex(ψ, Site(i)), rightindex(mpo, Site(i)))
-            new_inds = (physicalind, rightindex(ψ, Site(i)))
+            new_inds = (contractedind, rightindex(ψ, Site(i)))
         elseif i < L
             wanted_inds = (
                 physicalind,
@@ -678,14 +681,14 @@ function evolve(ψ::Chain, mpo::Chain)
                 rightindex(ψ, Site(i)),
                 rightindex(mpo, Site(i)),
             )
-            new_inds = (physicalind, leftindex(ψ, Site(i)), rightindex(ψ, Site(i)))
+            new_inds = (contractedind, leftindex(ψ, Site(i)), rightindex(ψ, Site(i)))
         else
             wanted_inds = (physicalind, leftindex(ψ, Site(i)), leftindex(mpo, Site(i)))
-            new_inds = (physicalind, leftindex(ψ, Site(i)))
+            new_inds = (contractedind, leftindex(ψ, Site(i)))
         end
 
         perm = Tenet.__find_index_permutation(wanted_inds, inds(t))
-        t = PermutedDimsArray(parent(t), perm)
+        t = permutedims(t, perm)
 
         t = Tensor(
             reshape(t, tuple(size(t, 1), [size(t, k) * size(t, k + 1) for k in 2:2:length(wanted_inds)]...)),
@@ -701,12 +704,18 @@ function evolve(ψ::Chain, mpo::Chain)
         end
     end
 
-    ψ_ev = MPS(updated_tensors)
-    for i in 1:L-1
-        push!(TensorNetwork(ψ_ev), Tensor(parent(Λ[i]), (rightindex(ψ_ev, Site(i)),)))
+
+    for i in 1:L
+        i < L && pop!(TensorNetwork(ψ), select(ψ, :between, Site(i), Site(i + 1)))
+        pop!(TensorNetwork(ψ), select(ψ, :tensor, Site(i)))
     end
 
-    return ψ_ev
+    for i in 1:L
+        i < L && push!(TensorNetwork(ψ), Λ[i])
+        push!(TensorNetwork(ψ), updated_tensors[i])
+    end
+
+    return ψ
 end
 
 function expect(ψ::Chain, observables)