add heisenberg script

Author: lkdvos

benchmark/MPSKitBenchmarks/scripts/setup_heisenberg.jl

@@ -0,0 +1,81 @@
+using TensorKit
+using MPSKit
+using MPSKit.BlockTensorKit: nonzero_keys
+using MPSKit.BlockTensorKit
+using MPSKitModels
+using TOML
+
+include(joinpath(@__DIR__, "..", "MPSKitBenchmarks.jl"))
+using .MPSKitBenchmarks
+# MPSKitBenchmarks.load!("derivatives")
+using .MPSKitBenchmarks.DerivativesBenchmarks: AC2Spec
+using .MPSKitBenchmarks.BenchUtils: tomlify
+
+# Utility functions
+# ----------------
+# setup "product state" -> ⨂^N |↑↓ - ↓↑⟩
+function initial_state(H)
+    @assert iseven(length(H))
+    @assert allequal(physicalspace(H))
+
+    pspace = physicalspace(H, 1)
+    A = rand(oneunit(pspace) ⊗ pspace^2 ← oneunit(pspace))
+    As = MPSKit.decompose_localmps(A)
+    return FiniteMPS(repeat(As, length(H) ÷ 2))
+end
+
+function generate_spaces(H, alg; D_min = 2, D_steps = 5)
+    # compute maximal spaces
+    psi_init = initial_state(H)
+    psi, = find_groundstate(psi_init, H, alg)
+
+    D_max = maximum(dim, left_virtualspace(psi))
+    Ds = round.(Int, logrange(D_min, D_max, D_steps))
+
+    return map(Ds) do D
+        mps = changebonds(psi, SvdCut(; trscheme = truncrank(D)))
+        return AC2Spec(mps, H)
+    end
+end
+
+# Parameters
+# ----------
+T = Float64
+spin = 1
+
+D_max = 10_000
+
+D_steps = 10
+D_min = 3
+
+
+# FiniteChain
+# -----------
+L = 100
+lattice = FiniteChain(L)
+
+symmetry = SU2Irrep
+alg = DMRG2(;
+    maxiter = 10, tol = 1.0e-12,
+    alg_eigsolve = (; tol = 1.0e-5, dynamic_tols = false, maxiter = 3),
+    trscheme = truncrank(D_max)
+)
+
+H = heisenberg_XXX(T, symmetry, lattice; spin);
+specs_su2 = generate_spaces(H, alg; D_min, D_steps)
+
+specs_triv = filter!(convert.(AC2Spec{ComplexSpace}, specs_su2)) do spec
+    dim(spec.mps_virtualspaces[1]) < 1000
+end
+
+specs_u1 = filter!(convert.(AC2Spec{U1Space}, specs_su2)) do spec
+    dim(spec.mps_virtualspaces[1]) < 5000
+end
+
+specs = vcat(specs_triv, specs_u1, specs_su2)
+
+output_file = joinpath(@__DIR__, "heisenberg_NN_specs.toml")
+open(output_file, "w") do io
+    TOML.print(io, Dict("specs" => tomlify.(specs)))
+end
+@info("Spaces written to $output_file")