data_[Na3Sn9Se18]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Na  0.9300  1.8000  1.1600
  Sn  1.9600  1.4500  0.8300
  Se  2.5500  1.1500  1.0133
]
_symmetry_space_group_name_H-M [R3]
_cell_length_a [7.0556]
_cell_length_b [7.0556]
_cell_length_c [19.3894]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [120.0000]
_symmetry_Int_Tables_number [146]
_chemical_formula_structural [Na(SnSe2)3]
_chemical_formula_sum '[Na3 Sn9 Se18]'
_cell_volume [835.9111]
_cell_formula_units_Z [3]
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
[
  Na  Na0  3  0.0000  0.0000  0.1383  1.0
  Sn  Sn1  3  0.0000  0.0000  0.3452  1.0
  Sn  Sn2  3  0.0000  0.0000  0.6601  1.0
  Sn  Sn3  3  0.0000  0.0000  0.8575  1.0
  Se  Se4  9  0.0186  0.6475  0.9176  1.0
  Se  Se5  9  0.0516  0.3536  0.4153  1.0
]