data_[Na4Ca4Si8]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Na  0.9300  1.8000  1.1600
  Ca  1.0000  1.8000  1.1400
  Si  1.9000  1.1000  0.5400
]
_symmetry_space_group_name_H-M [Cmcm]
_cell_length_a [4.4845]
_cell_length_b [13.2172]
_cell_length_c [6.5107]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [63]
_chemical_formula_structural [NaCaSi2]
_chemical_formula_sum '[Na4 Ca4 Si8]'
_cell_volume [385.9031]
_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  4  0.0000  0.2248  0.7500  1.0
  Ca  Ca1  4  0.0000  0.0562  0.2500  1.0
  Si  Si2  8  0.0000  0.4152  0.0685  1.0
]