Square lattice ferromagnet

The following codes could compute the spin wave dispersions of the ferromagnetic Heisenberg model on the square lattice.

using QuantumLattices
using TightBindingApproximation
using SpinWaveTheory
using Plots

lattice = Lattice([0.0, 0.0]; vectors=[[1.0, 0.0], [0.0, 1.0]])
hilbert = Hilbert(site=>Spin{1//2}() for site=1:length(lattice))
J = Heisenberg(:J, -1.0, 1)
magneticstructure = MagneticStructure(lattice, Dict(site=>[0, 0, 1] for site=1:length(lattice)))
ferromagnet = Algorithm(:SquareFM, LSWT(lattice, hilbert, J, magneticstructure))

path = ReciprocalPath(reciprocals(lattice), rectangle"Γ-X-M-Γ", length=100)
spectra = ferromagnet(
    :INSS,
    InelasticNeutronScatteringSpectra(path, range(0.0, 5.0, length=501); fwhm=0.2, rescale=x->log(1+x))
)
energybands = ferromagnet(:dispersion, EnergyBands(path))

plt = plot()
plot!(plt, spectra)
plot!(plt, energybands, color=:white, linestyle=:dash)