# SPDX-FileCopyrightText: 2021 The eminus developers
# SPDX-License-Identifier: Apache-2.0
from eminus import Atoms

# # The only necessary parameters are `atom` and `pos`
# # `atom` holds the atom symbols, and `pos` holds the atom positions
# # Please note that atomic units will be used
atom = "N2"
pos = [[-1.037, 0, 0], [1.037, 0, 0]]

# # Create an object for dinitrogen and display it
atoms = Atoms(atom, pos)
print(f"Atoms object:\n{atoms}\n")

# # Cut-off energy
ecut = 20

# # Optional parameters with examples are listed as follows
# # Cell size or vacuum size
a = 20

# # Spin of the system, i.e., the number of unpaired electrons (2S, not 2S+1)
spin = 0

# # Total charge of the system
charge = 0

# # Spin handling
unrestricted = False

# # Center the system inside the box by its geometric center of mass and rotate it such that its geometric moment of inertia aligns with the coordinate axes
center = True

# # Level of output, larger numbers mean more output
verbose = 4

# # Create an `Atoms` object for dinitrogen and display it
atoms = Atoms(
    atom=atom,
    pos=pos,
    ecut=ecut,
    a=a,
    spin=spin,
    charge=charge,
    unrestricted=unrestricted,
    center=center,
    verbose=verbose,
)
print(f"New Atoms object:\n{atoms}\n")

# # Albeit discouraged, some properties can be changed after the initialization as seen below
# # Valence charge per atom, the charges should not differ for the same species
# # `None` will use valence charges from GTH pseudopotentials
atoms.Z = [5, 5]

# # Real-space sampling of the cell using an equidistant grid
atoms.s = 40

# # Occupation numbers per state
# # `None` will assume occupations of 2
# # The last state will be adjusted if the sum of `f` is not equal to the sum of `Z`
atoms.f = [2, 2, 2, 2, 2]

# # You can manipulate the object by displaying or editing most properties
# # To display the calculated cell volume
print(f"Cell volume = {atoms.Omega} a0^3")

# # If you edit properties of an existing object dependent properties can be updated by rebuilding the `Atoms` object
# # The `atoms.build` function is used to generate cell parameters for an SCF calculation, but an SCF object will call the function if necessary
# # Edit the cell size, rebuild the object, and display the new cell volume
atoms.a = 3
atoms.build()
print(f"New cell volume = {atoms.Omega} a0^3")

# # To display all relevant electronic information regarding the occupations, one can display the `Occupations` object every `Atoms` object has
print(f"\nOccupations object:\n{atoms.occ}")

# # More information is always available in the respective docstring
# print(f"\nAtoms docstring:\n{Atoms.__doc__}")
# # or:
# help(Atoms)