data_[Mg12Se4]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Mg  1.3100  1.5000  0.8600
  Se  2.5500  1.1500  1.0133
]
_symmetry_space_group_name_H-M [Pnma]
_cell_length_a [6.4885]
_cell_length_b [8.3405]
_cell_length_c [6.8594]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [62]
_chemical_formula_structural [Mg3Se]
_chemical_formula_sum '[Mg12 Se4]'
_cell_volume [371.2141]
_cell_formula_units_Z [4]
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
[
  Mg  Mg0  8  0.2253  0.5458  0.0895  1
  Mg  Mg1  4  0.0078  0.7500  0.7603  1
  Se  Se2  4  0.0511  0.7500  0.3774  1
]