data_[Na4Nb2Se6]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Na  0.9300  1.8000  1.1600
  Nb  1.6000  1.4500  0.8200
  Se  2.5500  1.1500  1.0133
]
_symmetry_space_group_name_H-M [P-1]
_cell_length_a [6.7407]
_cell_length_b [6.7504]
_cell_length_c [7.3940]
_cell_angle_alpha [82.2299]
_cell_angle_beta [71.3829]
_cell_angle_gamma [61.2378]
_symmetry_Int_Tables_number [2]
_chemical_formula_structural [Na2NbSe3]
_chemical_formula_sum '[Na4 Nb2 Se6]'
_cell_volume [279.4346]
_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  0.1265  0.7010  0.4979  1.0
  Na  Na1  1  0.0000  0.0000  0.0000  1.0
  Na  Na2  1  0.5000  0.0000  0.5000  1.0
  Nb  Nb3  2  0.3614  0.3664  0.0034  1.0
  Se  Se4  2  0.0647  0.3747  0.7930  1.0
  Se  Se5  2  0.3059  0.9941  0.2048  1.0
  Se  Se6  2  0.4385  0.6403  0.7532  1.0
]