data_[Na8Cu20Si16]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Na  0.9300  1.8000  1.1600
  Cu  1.9000  1.3500  0.8200
  Si  1.9000  1.1000  0.5400
]
_symmetry_space_group_name_H-M [Fmmm]
_cell_length_a [5.2497]
_cell_length_b [9.2528]
_cell_length_c [14.5460]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [69]
_chemical_formula_structural [Na2Cu5Si4]
_chemical_formula_sum '[Na8 Cu20 Si16]'
_cell_volume [706.5665]
_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
[
  Na  Na0  8  0.0000  0.0000  0.1400  1
  Si  Si1  16  0.0000  0.1517  0.3714  1
  Cu  Cu2  8  0.2500  0.2500  0.0000  1
  Cu  Cu3  8  0.2500  0.2500  0.2500  1
  Cu  Cu4  4  0.0000  0.0000  0.5000  1
]