data_[Cu18Sn6Se18]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Cu  1.9000  1.3500  0.8200
  Sn  1.9600  1.4500  0.8300
  Se  2.5500  1.1500  1.0133
]
_symmetry_space_group_name_H-M [R-3]
_cell_length_a [6.9042]
_cell_length_b [6.9042]
_cell_length_c [20.9934]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [120.0000]
_symmetry_Int_Tables_number [148]
_chemical_formula_structural [Cu3SnSe3]
_chemical_formula_sum '[Cu18 Sn6 Se18]'
_cell_volume [866.6389]
_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
[
  Cu  Cu0  18  0.0069  0.3516  0.1301  1.0
  Sn  Sn1  6  0.0000  0.0000  0.3363  1.0
  Se  Se2  18  0.0061  0.3259  0.9148  1.0
]