Simplify 03

Author: kbarros

examples/03_LSWT_SU3_FeI2.jl

@@ -145,8 +145,8 @@ set_onsite_coupling!(sys, S -> -D*S[3]^2, 1)
 # This model has been fitted so that energy minimization yields the physically
 # correct ground state. Knowing this, we could manually set the magnetic
 # configuration by calling [`set_dipole!`](@ref) on each site in the system.
-# Instead, for pedagogy, we will search for the ground state using repeated
-# energy minimization.
+# Instead, for pedagogy, we will search for the ground state using energy
+# minimization.
 #
 # To reduce bias in the search, use [`resize_supercell`](@ref) to create a
 # relatively large system of 4×4×4 chemical cells. Call
@@ -162,20 +162,6 @@ minimize_energy!(sys)
 
 plot_spins(sys; color=[S[3] for S in sys.dipoles])
 
-# To search for the true ground state, a simple strategy is to repeatedly
-# randomize spins and then minimize their energy. The lowest-found energy
-# configuration is stored in `sys`.
-
-sys_min = clone_system(sys)
-for i in 1:100
-    randomize_spins!(sys)
-    minimize_energy!(sys)
-    if energy(sys) < energy(sys_min)
-        copy_spins!(sys_min, sys)
-    end
-end
-copy_spins!(sys, sys_min)
-
 # Use [`print_wrapped_intensities`](@ref) to get a quick summary of the static
 # structure factor. For simplicity, this function reports the sum of structure
 # factors ``\mathcal{S}^{αα}(𝐪)`` calculated for each sublattice ``α``
@@ -184,26 +170,24 @@ copy_spins!(sys, sys_min)
 
 print_wrapped_intensities(sys)
 
-# This is the correct ground state for FeI₂: a generalized spiral with
-# propagation wavevector ``𝐤 = ± [0, -1/4, 1/4]`` (equivalently ``±[1/4, 0,
-# 1/4]`` or ``±[-1/4, 1/4, 1/4]`` under 120° rotations). Subsequent calculations
-# can be made more efficient by working with a minimized magnetic cell. Find one
-# with [`suggest_magnetic_supercell`](@ref).
+# The correct ground state for FeI₂ is a generalized spiral with one of three
+# propagation wavevectors: ``𝐤 = ± [0, -1/4, 1/4]``, ``[1/4, 0, 1/4]``, or
+# ``[-1/4, 1/4, 1/4]``. These are related by 120° rotations. The result of
+# `print_wrapped_intensities` hints at this spiral phase.
+#
+# Let's break the 3-fold symmetry by hand. The function
+# [`suggest_magnetic_supercell`](@ref) takes any number of propagation
+# wavevectors and suggests a magnetic cell that is commensurate with them.
 
 suggest_magnetic_supercell([[0, -1/4, 1/4]])
 
-# Create a minimized system with [`reshape_supercell`](@ref). Here, the ground
-# state is found rapidly. A good consistency check is that the
-# [`energy_per_site`](@ref) is unchanged by the reshaping.
+# After calling [`reshape_supercell`](@ref), it becomes easy to find the ground
+# state. Plot the system again, now including "ghost" spins out to 12Å. The
+# correct two-up, two-down magnetic order is visually apparent.
 
 sys_min = reshape_supercell(sys, [1 0 0; 0 1 -2; 0 1 2])
 randomize_spins!(sys_min)
 minimize_energy!(sys_min)
-@assert energy_per_site(sys_min) ≈ energy_per_site(sys)
-
-# Plot the system again, now including "ghost" spins out to 12Å. The correct
-# two-up, two-down magnetic order is visually apparent.
-
 plot_spins(sys_min; color=[S[3] for S in sys_min.dipoles], ghost_radius=12)
 
 # ### Spin wave theory