/
fourier_transforms.jl
49 lines (37 loc) · 1.64 KB
/
fourier_transforms.jl
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using Test
using DFTK: PlaneWaveBasis, G_to_r!, r_to_G!, G_to_r, r_to_G
include("testcases.jl")
@testset "FFT and IFFT are an identity" begin
Ecut = 4.0 # Hartree
fft_size = [8, 8, 8]
model = Model(silicon.lattice, n_electrons=silicon.n_electrons)
pw = PlaneWaveBasis(model, Ecut, silicon.kcoords, silicon.ksymops; fft_size=fft_size)
@testset "Transformation on the cubic basis set" begin
f_G = Array{ComplexF64}(randn(Float64, pw.fft_size...))
f_R = Array{ComplexF64}(undef, pw.fft_size...)
G_to_r!(f_R, pw, f_G)
f2_G = r_to_G(pw, f_R)
f2_R = G_to_r(pw, f2_G; assume_real=false)
f3_G = r_to_G!(similar(f_R), pw, f_R)
@test maximum(abs.(f2_G - f_G)) < 1e-12
@test maximum(abs.(f2_R - f_R)) < 1e-12
@test maximum(abs.(f3_G - f_G)) < 1e-12
G_to_r_mat = DFTK.G_to_r_matrix(pw)
r_to_G_mat = DFTK.r_to_G_matrix(pw)
@test maximum(abs.(G_to_r_mat * r_to_G_mat - I)) < 1e-12
@test maximum(abs.(G_to_r_mat * vec(f_G) - vec(f_R))) < 1e-12
@test maximum(abs.(r_to_G_mat * vec(f_R) - vec(f_G))) < 1e-12
end
@testset "Transformation on the spherical basis set" begin
kpt = pw.kpoints[2]
f_G = Array{ComplexF64}(randn(Float64, length(G_vectors(kpt))))
f_R = Array{ComplexF64}(undef, pw.fft_size...)
G_to_r!(f_R, pw, kpt, f_G)
f2_G = similar(f_G)
r_to_G!(f2_G, pw, kpt, copy(f_R)) # copy needed, because r_to_G! destructive
f2_R = similar(f_R)
G_to_r!(f2_R, pw, kpt, f2_G)
@test maximum(abs.(f2_G - f_G)) < 1e-12
@test maximum(abs.(f2_R - f_R)) < 1e-12
end
end