data_[Na4Cl2O8]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Na  0.9300  1.8000  1.1600
  Cl  3.1600  1.0000  0.7800
  O  3.4400  0.6000  1.2600
]
_symmetry_space_group_name_H-M [I4mm]
_cell_length_a [5.5547]
_cell_length_b [5.5547]
_cell_length_c [6.5145]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [107]
_chemical_formula_structural [Na2ClO4]
_chemical_formula_sum '[Na4 Cl2 O8]'
_cell_volume [201.0005]
_cell_formula_units_Z [2]
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  4  0.0000  0.5000  0.2498  1
  Cl  Cl1  2  0.0000  0.0000  0.0525  1
  O  O2  8  0.2030  0.2030  0.9865  1
]