using DFTK
using Unitful
using Plots
using LazyArtifacts
import Main: @artifact_str # hide

psp_hgh  = load_psp("hgh/lda/si-q4.hgh");
psp_upf  = load_psp(artifact"pd_nc_sr_lda_standard_0.4.1_upf/Si.upf");

function run_bands(psp)
    a = 10.26  # Silicon lattice constant in Bohr
    lattice = a / 2 * [[0 1 1.];
                       [1 0 1.];
                       [1 1 0.]]
    Si = ElementPsp(:Si; psp=psp)
    atoms     = [Si, Si]
    positions = [ones(3)/8, -ones(3)/8]

    # These are (as you saw above) completely unconverged parameters
    model = model_LDA(lattice, atoms, positions; temperature=1e-2)
    basis = PlaneWaveBasis(model; Ecut=12, kgrid=(4, 4, 4))

    scfres   = self_consistent_field(basis; tol=1e-4)
    bandplot = plot_bandstructure(scfres)
    (; scfres, bandplot)
end;

result_hgh = run_bands(psp_hgh)
result_hgh.scfres.energies

result_upf = run_bands(psp_upf)
result_upf.scfres.energies

plot(result_hgh.bandplot, result_upf.bandplot, titles=["HGH" "UPF"], size=(800, 400))