data_[Pm18Mg6Si12]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Pm  1.1300  1.8500  1.1100
  Mg  1.3100  1.5000  0.8600
  Si  1.9000  1.1000  0.5400
]
_symmetry_space_group_name_H-M [R-3c]
_cell_length_a [7.7824]
_cell_length_b [7.7824]
_cell_length_c [19.2652]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [120.0000]
_symmetry_Int_Tables_number [167]
_chemical_formula_structural [Pm3MgSi2]
_chemical_formula_sum '[Pm18 Mg6 Si12]'
_cell_volume [1010.4796]
_cell_formula_units_Z [6]
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
[
  Pm  Pm0  18  0.0000  0.2808  0.7500  1
  Mg  Mg1  6  0.0000  0.0000  0.0000  1
  Si  Si2  12  0.0000  0.0000  0.1436  1
]