Fix formatting, fix convention of Ising model

QuantumKitHub · Jul 15, 2024 · df4fa10 · df4fa10
1 parent 4713c11
commit df4fa10
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Showing 2 changed files with 19 additions and 13 deletions.
diff --git a/src/operators/models.jl b/src/operators/models.jl
@@ -13,9 +13,9 @@ function square_lattice_tf_ising(
     lattice = fill(physical_space, 1, 1)
     σx = TensorMap(T[0 1; 1 0], physical_space, physical_space)
     σz = TensorMap(T[1 0; 0 -1], physical_space, physical_space)
-    hzz = nearest_neighbour_hamiltonian(lattice, -J / 4 * σz ⊗ σz)
+    hzz = nearest_neighbour_hamiltonian(lattice, -J * σz ⊗ σz)
     return repeat(
-        LocalOperator(lattice, hzz.terms..., (CartesianIndex(1, 1),) => -J * h / 2 * σx),
+        LocalOperator(lattice, hzz.terms..., (CartesianIndex(1, 1),) => -J * h * σx),
         unitcell...,
     )
 end

diff --git a/test/tf_ising.jl b/test/tf_ising.jl
@@ -11,19 +11,25 @@ using OptimKit
 # J. Jordan, R. Orús, G. Vidal, F. Verstraete, and J. I. Cirac
 # Phys. Rev. Lett. 101, 250602 – Published 18 December 2008
 # (values estimated from plots)
-# (factor of 2 in the energy and magnetisation due to convention differences)
-h = 0.5
-e = -0.525
-mᶻ = 0.98
+# (factor of 2 in the energy due to convention differences)
+h = 3.1
+e = -1.6417 * 2
+mˣ = 0.91
 
 # initialize parameters
 χbond = 2
 χenv = 16
-ctm_alg = CTMRG(; trscheme=truncdim(χenv), tol=1e-10, miniter=4, maxiter=100, verbosity=2)
+ctm_alg = CTMRG(;
+    tol=1e-10,
+    miniter=4,
+    maxiter=100,
+    verbosity=2,
+    svd_alg=SVDAdjoint(; fwd_alg=TensorKit.SVD(), rrule_alg=GMRES(; tol=1e-10)),
+)
 opt_alg = PEPSOptimize(;
     boundary_alg=ctm_alg,
-    optimizer=LBFGS(4; maxiter=100, gradtol=1e-3, verbosity=2),
-    gradient_alg=LinSolver(; solver=GMRES(; tol=1e-6, maxiter=100))
+    optimizer=LBFGS(4; maxiter=100, gradtol=1e-4, verbosity=2),
+    gradient_alg=LinSolver(; solver=GMRES(; tol=1e-6, maxiter=100)),
     reuse_env=true,
 )
 
@@ -36,10 +42,10 @@ env_init = leading_boundary(CTMRGEnv(psi_init, ComplexSpace(χenv)), psi_init, c
 result = fixedpoint(psi_init, H, opt_alg, env_init)
 
 # compute magnetization
-σz = TensorMap(scalartype(psi_init)[1 0; 0 -1], ℂ^2, ℂ^2)
-M = LocalOperator(H.lattice, (CartesianIndex(1, 1),) => σz)
+σx = TensorMap(scalartype(psi_init)[0 1; 1 0], ℂ^2, ℂ^2)
+M = LocalOperator(H.lattice, (CartesianIndex(1, 1),) => σx)
 magn = expectation_value(result.peps, M, result.env)
 
-@test result.E ≈ e atol = 5e-2
+@test result.E ≈ e atol = 1e-3
 @test imag(magn) ≈ 0 atol = 1e-6
-@test abs(magn) ≈ mᶻ atol = 5e-2
+@test abs(magn) ≈ mˣ atol = 5e-2