data_[Na2Ni4Se4]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Na  0.9300  1.8000  1.1600
  Ni  1.9100  1.3500  0.7400
  Se  2.5500  1.1500  1.0133
]
_symmetry_space_group_name_H-M [I4/mmm]
_cell_length_a [3.8408]
_cell_length_b [3.8408]
_cell_length_c [12.4018]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [139]
_chemical_formula_structural [Na(NiSe)2]
_chemical_formula_sum '[Na2 Ni4 Se4]'
_cell_volume [182.9524]
_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  2  0.0000  0.0000  0.0000  1.0
  Ni  Ni1  4  0.0000  0.5000  0.2500  1.0
  Se  Se2  4  0.0000  0.0000  0.3628  1.0
]