The structure described by BaO2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(4), and three equivalent O(2) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ba(2), and one O(4) atom to form a mixture of distorted corner and edge-sharing OBa4O square pyramids. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Ba(2), three equivalent Ba(1), and one O(3) atom. In the third O site, O(3) is bonded to two equivalent Ba(1), two equivalent Ba(2), and one O(2) atom to form a mixture of distorted corner and edge-sharing OBa4O square pyramids. In the fourth O site, O(4) is bonded to two equivalent Ba(1), two equivalent Ba(2), and one O(1) atom to form a mixture of distorted corner and edge-sharing OBa4O trigonal bipyramids. is represented by the CIF card [CIF]
data_BaO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.745
_cell_length_b   7.841
_cell_length_c   8.178
_cell_angle_alpha   60.444
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   432.037
_cell_formula_units_Z   8
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
  Ba  Ba0  1  0.144  0.493  0.688  1.0
  Ba  Ba1  1  0.356  0.493  0.188  1.0
  Ba  Ba2  1  0.856  0.507  0.312  1.0
  Ba  Ba3  1  0.644  0.507  0.812  1.0
  Ba  Ba4  1  0.011  0.958  0.770  1.0
  Ba  Ba5  1  0.489  0.958  0.270  1.0
  Ba  Ba6  1  0.989  0.042  0.230  1.0
  Ba  Ba7  1  0.511  0.042  0.730  1.0
  O  O8  1  0.890  0.776  0.596  1.0
  O  O9  1  0.610  0.776  0.096  1.0
  O  O10  1  0.110  0.224  0.404  1.0
  O  O11  1  0.390  0.224  0.904  1.0
  O  O12  1  0.813  0.278  0.691  1.0
  O  O13  1  0.687  0.278  0.191  1.0
  O  O14  1  0.187  0.722  0.309  1.0
  O  O15  1  0.313  0.722  0.809  1.0
  O  O16  1  0.890  0.223  0.878  1.0
  O  O17  1  0.610  0.223  0.378  1.0
  O  O18  1  0.110  0.777  0.122  1.0
  O  O19  1  0.390  0.777  0.622  1.0
  O  O20  1  0.717  0.744  0.960  1.0
  O  O21  1  0.783  0.744  0.460  1.0
  O  O22  1  0.283  0.256  0.040  1.0
  O  O23  1  0.217  0.256  0.540  1.0
[/CIF]
.
The structure described by BaO2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 9-coordinate geometry to two equivalent O(1), two equivalent O(3), two equivalent O(4), and three equivalent O(2) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ba(2), and one O(4) atom to form a mixture of distorted corner and edge-sharing OBa4O square pyramids. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Ba(2), three equivalent Ba(1), and one O(3) atom. In the third O site, O(3) is bonded to two equivalent Ba(1), two equivalent Ba(2), and one O(2) atom to form a mixture of distorted corner and edge-sharing OBa4O square pyramids. In the fourth O site, O(4) is bonded to two equivalent Ba(1), two equivalent Ba(2), and one O(1) atom to form a mixture of distorted corner and edge-sharing OBa4O trigonal bipyramids. is represented by the CIF card [CIF]
data_BaO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.745
_cell_length_b   7.841
_cell_length_c   8.178
_cell_angle_alpha   60.444
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   432.037
_cell_formula_units_Z   8
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
  Ba  Ba0  1  0.144  0.493  0.688  1.0
  Ba  Ba1  1  0.356  0.493  0.188  1.0
  Ba  Ba2  1  0.856  0.507  0.312  1.0
  Ba  Ba3  1  0.644  0.507  0.812  1.0
  Ba  Ba4  1  0.011  0.958  0.770  1.0
  Ba  Ba5  1  0.489  0.958  0.270  1.0
  Ba  Ba6  1  0.989  0.042  0.230  1.0
  Ba  Ba7  1  0.511  0.042  0.730  1.0
  O  O8  1  0.890  0.776  0.596  1.0
  O  O9  1  0.610  0.776  0.096  1.0
  O  O10  1  0.110  0.224  0.404  1.0
  O  O11  1  0.390  0.224  0.904  1.0
  O  O12  1  0.813  0.278  0.691  1.0
  O  O13  1  0.687  0.278  0.191  1.0
  O  O14  1  0.187  0.722  0.309  1.0
  O  O15  1  0.313  0.722  0.809  1.0
  O  O16  1  0.890  0.223  0.878  1.0
  O  O17  1  0.610  0.223  0.378  1.0
  O  O18  1  0.110  0.777  0.122  1.0
  O  O19  1  0.390  0.777  0.622  1.0
  O  O20  1  0.717  0.744  0.960  1.0
  O  O21  1  0.783  0.744  0.460  1.0
  O  O22  1  0.283  0.256  0.040  1.0
  O  O23  1  0.217  0.256  0.540  1.0
[/CIF]
.