Atoms without orbitals? #449
Description
I am trying to build a geometry for which I would like to have zero orbitals associated to certain atoms. Can it be done?
As far as I can see, I get at least one orbital associated to an atom:
>>> print(sisl.Atom('H', orbitals=0))
Atom{H, Z: 1, mass(au): 1.00794, maxR: 0.00000,
Orbital{R: 0.00000, q0: 0.0}
}
>>> print(sisl.Atom('H', orbitals=(0, 1)))
Atom{H, Z: 1, mass(au): 1.00794, maxR: 1.00000,
Orbital{R: 0.00000, q0: 0.0},
Orbital{R: 1.00000, q0: 0.0}
}
>>> print(sisl.Atom('H', orbitals=[]))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "~/.local/lib/python3.8/site-packages/sisl/atom.py", line 1013, in __init__
raise ValueError(f"{self.__class__.__name__}.__init__ got unparseable 'orbitals' argument: {orbitals}")
ValueError: Atom.__init__ got unparseable 'orbitals' argument: []Motivation: Think of a GNR structure with H-atoms at the edges (it could be a geometry obtained from DFT). Now, if we could simply set zero orbitals for the H and one orbital for C, we would readily arrive at the effective model for the pi-electrions only, without having to remove any physical atoms from the geometry.