clean up changebonds with Multiline

Author: lkdvos

src/algorithms/changebonds/changebonds.jl

@@ -9,6 +9,14 @@ See also: [`SvdCut`](@ref), [`RandExpand`](@ref), [`VUMPSSvdCut`](@ref), [`Optim
 function changebonds end
 function changebonds! end
 
+# write in terms of MultilineMPS
+function changebonds(ψ::InfiniteMPS, operator::InfiniteMPO, alg,
+                     envs=environments(ψ, operator))
+    ψ′, envs′ = changebonds(convert(MultilineMPS, ψ), convert(MultilineMPO, operator), alg,
+                            Multiline([envs]))
+    return convert(InfiniteMPS, ψ′), envs
+end
+
 _expand(ψ, AL′, AR′) = _expand!(copy(ψ), AL′, AR′)
 function _expand!(ψ::InfiniteMPS, AL′::PeriodicVector, AR′::PeriodicVector)
     for i in 1:length(ψ)

src/algorithms/changebonds/optimalexpand.jl

@@ -13,7 +13,8 @@ original ψ.
     trscheme::TruncationScheme = truncdim(1)
 end
 
-function changebonds(ψ::InfiniteMPS, H, alg::OptimalExpand, envs=environments(ψ, H))
+function changebonds(ψ::InfiniteMPS, H::InfiniteMPOHamiltonian, alg::OptimalExpand,
+                     envs=environments(ψ, H))
     T = eltype(ψ.AL)
     AL′ = similar(ψ.AL)
     AR′ = similar(ψ.AR, tensormaptype(spacetype(T), 1, numind(T) - 1, storagetype(T)))
@@ -36,12 +37,6 @@ function changebonds(ψ::InfiniteMPS, H, alg::OptimalExpand, envs=environments(
     return newψ, envs
 end
 
-function changebonds(ψ::InfiniteMPS, H::DenseMPO, alg::OptimalExpand,
-                     envs=environments(ψ, H))
-    (nmψ, envs) = changebonds(convert(MultilineMPS, ψ), convert(MultilineMPO, H), alg, envs)
-    return (convert(InfiniteMPS, nmψ), envs)
-end
-
 function changebonds(ψ::MultilineMPS, H, alg::OptimalExpand, envs=environments(ψ, H))
     TL = eltype(ψ.AL)
     AL′ = PeriodicMatrix{TL}(undef, size(ψ.AL))

src/algorithms/changebonds/vumpssvd.jl

@@ -26,8 +26,8 @@ function changebonds_1(state::InfiniteMPS, H, alg::VUMPSSvdCut,
 
     nstate, nenvs = changebonds(nstate, nH, alg)
 
-    D1 = space(nstate.AL[1], 1)
-    D2 = space(nstate.AL[2], 1)
+    D1 = left_virtualspace(nstate, 1)
+    D2 = left_virtualspace(nstate, 2)
 
     # collapse back to 1 site
     if D2 != D1
@@ -36,6 +36,7 @@ function changebonds_1(state::InfiniteMPS, H, alg::VUMPSSvdCut,
     end
 
     collapsed = InfiniteMPS([nstate.AL[1]], nstate.C[1]; tol=alg.tol_gauge)
+    recalculate!(envs, collapsed, H, collapsed)
 
     return collapsed, envs
 end
@@ -72,8 +73,8 @@ function changebonds_n(state::InfiniteMPS, H, alg::VUMPSSvdCut, envs=environment
         copied[loc] = AL1
         copied[loc + 1] = AL2
         state = InfiniteMPS(copied; tol=alg.tol_gauge)
+        recalculate!(envs, state, H, state)
     end
-
     return state, envs
 end