data_[Na2Ca2Er2]
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
  Er  1.2400  1.7500  1.0300
]
_symmetry_space_group_name_H-M [P4/nmm]
_cell_length_a [3.6648]
_cell_length_b [3.6648]
_cell_length_c [16.0971]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [129]
_chemical_formula_structural [NaCaEr]
_chemical_formula_sum '[Na2 Ca2 Er2]'
_cell_volume [216.2003]
_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  0.5000  0.5850  1
  Ca  Ca1  2  0.0000  0.5000  0.2346  1
  Er  Er2  2  0.0000  0.5000  0.9307  1
]