bilayer

sisl.geom.bilayer(bond=1.42, bottom_atoms=None, top_atoms=None, stacking='AB', twist=(0, 0), separation=3.35, vacuum=20, *, layer='both', ret_angle=False)

Commensurate unit cell of a hexagonal bilayer structure, possibly with a twist angle.

This routine follows the prescription of twisted bilayer graphene found in [13].

Notes

This routine may change in the future to force some of the arguments.

Parameters:

bond (float) – bond length between atoms in the honeycomb lattice
bottom_atoms (Optional[AtomsLike]) – atom (or atoms) in the bottom layer. Defaults to Atom(6)
top_atoms (Optional[AtomsLike]) – atom (or atoms) in the top layer, defaults to bottom_atom
stacking (Literal['AB', 'AA', 'BA']) – stacking sequence of the bilayer, where XY means that site X in bottom layer coincides with site Y in top layer
twist (tuple of int, optional) – integer coordinates (m, n) defining a commensurate twist angle
separation (float) – distance between the two layers
vacuum (float) – length of vacuum region (along 3rd lattice vector)
layer (Literal['both', 'bottom', 'top']) – control which layer(s) to return
ret_angle (bool) – return the twist angle (in degrees) in addition to the geometry instance

Return type:

Geometry