using DFTK

# Construct bulk system and convert to an AbstractSystem
using ASEconvert
system_ase = ase.build.bulk("Si")
system = pyconvert(AbstractSystem, system_ase)

system = attach_psp(system; Si="hgh/lda/si-q4")

model  = model_LDA(system; temperature=1e-3)
basis  = PlaneWaveBasis(model; Ecut=15, kgrid=[4, 4, 4])
scfres = self_consistent_field(basis, tol=1e-8);

using AtomsIO

# Read a file using [AtomsIO](https://github.com/mfherbst/AtomsIO.jl),

system = load_system("Si.extxyz")

# Now run the LDA calculation:
system = attach_psp(system; Si="hgh/lda/si-q4")
model  = model_LDA(system; temperature=1e-3)
basis  = PlaneWaveBasis(model; Ecut=15, kgrid=[4, 4, 4])
scfres = self_consistent_field(basis, tol=1e-8);

using AtomsBase
using Unitful
using UnitfulAtomic

# Construct a system in the AtomsBase world
a = 10.26u"bohr"  # Silicon lattice constant
lattice = a / 2 * [[0, 1, 1.],  # Lattice as vector of vectors
                   [1, 0, 1.],
                   [1, 1, 0.]]
atoms  = [:Si => ones(3)/8, :Si => -ones(3)/8]
system = periodic_system(atoms, lattice; fractional=true)

# Now run the LDA calculation:
system = attach_psp(system; Si="hgh/lda/si-q4")
model  = model_LDA(system; temperature=1e-3)
basis  = PlaneWaveBasis(model; Ecut=15, kgrid=[4, 4, 4])
scfres = self_consistent_field(basis, tol=1e-4);

second_system = atomic_system(model)

lattice = 5.431u"Å" / 2 * [[0 1 1.];
                           [1 0 1.];
                           [1 1 0.]];
Si = ElementPsp(:Si, psp=load_psp("hgh/lda/Si-q4"))
atoms     = [Si, Si]
positions = [ones(3)/8, -ones(3)/8]

third_system = atomic_system(lattice, atoms, positions)