data_[Na18Zn3Hg6]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Na  0.9300  1.8000  1.1600
  Zn  1.6500  1.3500  0.8800
  Hg  2.0000  1.5000  1.2450
]
_symmetry_space_group_name_H-M [R-3m]
_cell_length_a [5.4187]
_cell_length_b [5.4187]
_cell_length_c [30.7031]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [120.0000]
_symmetry_Int_Tables_number [166]
_chemical_formula_structural [Na6ZnHg2]
_chemical_formula_sum '[Na18 Zn3 Hg6]'
_cell_volume [780.7469]
_cell_formula_units_Z [3]
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  6  0.0000  0.0000  0.1911  1.0
  Na  Na1  6  0.0000  0.0000  0.3028  1.0
  Na  Na2  6  0.0000  0.0000  0.4233  1.0
  Zn  Zn3  3  0.0000  0.0000  0.0000  1.0
  Hg  Hg4  6  0.0000  0.0000  0.0888  1.0
]