data_[K2Rb4Nb2O8]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  K  0.8200  2.2000  1.5200
  Rb  0.8200  2.3500  1.6600
  Nb  1.6000  1.4500  0.8200
  O  3.4400  0.6000  1.2600
]
_symmetry_space_group_name_H-M [Pmn2_1]
_cell_length_a [8.1900]
_cell_length_b [7.3199]
_cell_length_c [6.5202]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [90.0000]
_symmetry_Int_Tables_number [31]
_chemical_formula_structural [KRb2NbO4]
_chemical_formula_sum '[K2 Rb4 Nb2 O8]'
_cell_volume [390.8861]
_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
[
  Rb  Rb0  4  0.2431  0.6806  0.9897  1
  K  K1  2  0.0000  0.8521  0.4918  1
  Nb  Nb2  2  0.0000  0.1755  0.0032  1
  O  O3  4  0.1908  0.3020  0.9214  1
  O  O4  2  0.0000  0.1606  0.2907  1
  O  O5  2  0.0000  0.9372  0.8920  1
]