data_[Nb2Hg8O4]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Nb  1.6000  1.4500  0.8200
  Hg  2.0000  1.5000  1.2450
  O  3.4400  0.6000  1.2600
]
_symmetry_space_group_name_H-M [I4/mmm]
_cell_length_a [5.4415]
_cell_length_b [5.4415]
_cell_length_c [12.3493]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [139]
_chemical_formula_structural [Nb(Hg2O)2]
_chemical_formula_sum '[Nb2 Hg8 O4]'
_cell_volume [365.6667]
_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
[
  Nb  Nb0  2  0.0000  0.0000  0.0000  1
  Hg  Hg1  4  0.0000  0.0000  0.2233  1
  Hg  Hg2  4  0.0000  0.5000  0.0000  1
  O  O3  4  0.0000  0.0000  0.3913  1
]