data_NaNiO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.57
_cell_length_b   5.57
_cell_length_c   5.57
_cell_angle_alpha   31.32
_cell_angle_beta   31.32
_cell_angle_gamma   31.32
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaNiO2
_chemical_formula_sum   'Na1 Ni1 O2'
_cell_volume   41.35
_cell_formula_units_Z   1
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  1  0.0  0.0  0.0  1.0
  Ni  Ni1  1  0.0  0.0  0.93  1.0
  O  O2  1  0.0  0.0  0.68  1.0
  O  O3  1  0.0  0.0  0.19  1.0

data_NaNiO2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.2
_cell_length_b   3.0
_cell_length_c   5.57
_cell_angle_alpha   90.0
_cell_angle_beta   108.16
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   NaNiO2
_chemical_formula_sum   'Na2 Ni2 O4'
_cell_volume   82.69
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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  0.0  0.0  0.0  1.0
  Ni  Ni1  2  0.0  0.0  0.07  1.0
  O  O2  2  0.0  0.0  0.32  1.0
  O  O3  2  0.0  0.0  0.81  1.0

Na Ni O O