def _get_ring(crystal: Crystal, miller_indices: MillerIndices,
min_sf: float) -> Union[CrystalRing, None]:
scattering_vector = crystal.scattering_vector(miller_indices)
q = np.linalg.norm(scattering_vector)
sf = _calc_structure_factor(
q, miller_indices, crystal) * _structure_factor_coef(miller_indices)
if sf >= min_sf:
return CrystalRing(radius=q,
miller_indices=miller_indices,
intensity=sf,
crystal=crystal)
def get_crystal_rings(crystal: Crystal,
q_max: float,
min_sf: float = 0.01) -> Tuple[CrystalRing, ...]:
ring_list: List[CrystalRing] = []
atom_list = [(str(atom), atom.coords_fractional) for atom in crystal]
for miller_indices in crystal.bounded_reflections(q_max):
if np.all(np.array(miller_indices) >= 0):
scattering_vector = crystal.scattering_vector(miller_indices)
q = np.linalg.norm(scattering_vector)
sf = _calc_structure_factor(scattering_vector, miller_indices,
atom_list)
if sf >= min_sf:
ring_list.append(
CrystalRing(radius=q,
miller_indices=miller_indices,
intensity=sf,
crystal=crystal))
ring_list.sort(key=lambda ring: ring.radius)
return tuple(ring_list)
