Remove functionalities that were merged into NamedGraphs.jl

Extend `models.jl` and remove `test/utils.jl`

Change lazy `inner` to explicit `inner_network`

Author: leburgel

src/ITensorNetworks.jl

@@ -113,7 +113,6 @@ const UniformDataGraph{D} = NamedDimDataGraph{
 }
 
 include("utils.jl")
-include("namedgraphs.jl")
 include("itensors.jl")
 include("partition.jl")
 include("lattices.jl")
@@ -135,7 +134,6 @@ include(joinpath("treetensornetwork", "opsum_to_ttno.jl"))
 include(joinpath("treetensornetwork", "abstractprojttno.jl"))
 include(joinpath("treetensornetwork", "projttno.jl"))
 include(joinpath("treetensornetwork", "projttnosum.jl"))
-include(joinpath("graphs", "namedgraphs.jl"))
 include("utility.jl")
 
 include("exports.jl")

src/abstractitensornetwork.jl

@@ -546,7 +546,7 @@ function norm_network(tn::AbstractITensorNetwork; kwargs...)
 end
 
 function flattened_inner_network(ϕ::AbstractITensorNetwork, ψ::AbstractITensorNetwork)
-  tn = inner(prime(ϕ; sites=[]), ψ)
+  tn = inner_network(prime(ϕ; sites=[]), ψ)
   for v in vertices(ψ)
     tn = contract(tn, (2, v...) => (1, v...))
   end
@@ -559,7 +559,7 @@ function contract_inner(
   sequence=nothing,
   contraction_sequence_kwargs=(;),
 )
-  tn = inner(prime(ϕ; sites=[]), ψ)
+  tn = inner_network(prime(ϕ; sites=[]), ψ)
   # TODO: convert to an IndsNetwork and compute the contraction sequence
   for v in vertices(ψ)
     tn = contract(tn, (2, v...) => (1, v...))

src/exports.jl

@@ -88,6 +88,7 @@ export AbstractITensorNetwork,
   # namedgraphs.jl
   rename_vertices,
   # models.jl
+  heisenberg,
   ising,
   # opsum.jl
   group_terms,

src/graphs/namedgraphs.jl

@@ -1,10 +1,78 @@
-function ising(g::AbstractGraph; h)
+_maybe_fill(x, n) = x
+_maybe_fill(x::Number, n) = fill(x, n)
+
+"""
+Random field J1-J2 Heisenberg model on a general graph
+"""
+function heisenberg(
+  g::AbstractGraph; J1=1.0, J2=0.0, h::Union{<:Real,Vector{<:Real}}=0
+)
+  h = _maybe_fill(h, nv(g))
   ℋ = OpSum()
-  for e in edges(g)
-    ℋ -= "Z", maybe_only(src(e)), "Z", maybe_only(dst(e))
+  if !iszero(J1)
+    for e in edges(g)
+      ℋ += J1 / 2, "S+", maybe_only(src(e)), "S-", maybe_only(dst(e))
+      ℋ += J1 / 2, "S-", maybe_only(src(e)), "S+", maybe_only(dst(e))
+      ℋ += J1, "Sz", maybe_only(src(e)), "Sz", maybe_only(dst(e))
+    end
   end
-  for v in vertices(g)
-    ℋ += h, "X", maybe_only(v)
+  if !iszero(J2)
+    # TODO, more clever way of looping over next to nearest neighbors?
+    for (i, v) in enumerate(vertices(g))
+      nnn = [neighbors(g, n) for n in neighbors(g, v)]
+      nnn = setdiff(Base.Iterators.flatten(nnn), neighbors(g, v))
+      nnn = setdiff(nnn, vertices(g)[1:i])
+      for nn in nnn
+        ℋ += J2 / 2, "S+", maybe_only(v), "S-", maybe_only(nn)
+        ℋ += J2 / 2, "S-", maybe_only(v), "S+", maybe_only(nn)
+        ℋ += J2, "Sz", maybe_only(v), "Sz", maybe_only(nn)
+      end
+    end
+  end
+  for (i, v) in enumerate(vertices(g))
+    if !iszero(h[i])
+      ℋ -= h[i], "Sz", maybe_only(v)
+    end
+  end
+  return ℋ
+end
+
+"""
+Next-to-nearest-neighbor Ising model (ZZX) on a general graph
+"""
+function ising(g::AbstractGraph; J1=-1.0, J2=0.0, h::Union{<:Real,Vector{<:Real}}=0)
+  h = _maybe_fill(h, nv(g))
+  ℋ = OpSum()
+  if !iszero(J1)
+    for e in edges(g)
+      ℋ += J1, "Z", maybe_only(src(e)), "Z", maybe_only(dst(e))
+    end
+  end
+  if !iszero(J2)
+    # TODO, more clever way of looping over next to nearest neighbors?
+    for (i, v) in enumerate(vertices(g))
+      nnn = [neighbors(g, n) for n in neighbors(g, v)]
+      nnn = setdiff(Base.Iterators.flatten(nnn), neighbors(g, v))
+      nnn = setdiff(nnn, vertices(g)[1:i])
+      for nn in nnn
+        ℋ += J2, "Z", maybe_only(v), "Z", maybe_only(nn)
+      end
+    end
+  end
+  for (i, v) in enumerate(vertices(g))
+    if !iszero(h[i])
+      ℋ += h[i], "X", maybe_only(v)
+    end
   end
   return ℋ
 end
+
+"""
+Random field J1-J2 Heisenberg model on a chain of length N
+"""
+heisenberg(N::Integer; kwargs...) = heisenberg(grid((N,)); kwargs...)
+
+"""
+Next-to-nearest-neighbor Ising model (ZZX) on a chain of length N
+"""
+ising(N::Integer; kwargs...) = ising(grid((N,)); kwargs...)