data_[Na4Cu12Si8]
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 [Imm2]
_cell_length_a [6.8381]
_cell_length_b [9.4680]
_cell_length_c [5.6960]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [44]
_chemical_formula_structural [NaCu3Si2]
_chemical_formula_sum '[Na4 Cu12 Si8]'
_cell_volume [368.7821]
_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  2  0.0000  0.0000  0.0530  1.0
  Na  Na1  2  0.0000  0.5000  0.4907  1.0
  Cu  Cu2  8  0.1920  0.2450  0.2525  1.0
  Si  Si3  4  0.0000  0.1361  0.5678  1.0
  Si  Si4  4  0.0000  0.2976  0.9194  1.0
  Cu  Cu5  4  0.1999  0.5000  0.9860  1.0
]