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 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Ba site, Ba(2) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(2), 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) and two equivalent Ba(2) atoms to form a mixture of corner and edge-sharing OBa4 tetrahedra. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to two equivalent Ba(1) and two equivalent Ba(2) atoms. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Ba(2) and two equivalent Ba(1) atoms. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to two equivalent Ba(1) and two equivalent Ba(2) atoms. is represented by the CIF card [CIF]
data_BaO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.348
_cell_length_b   7.955
_cell_length_c   7.084
_cell_angle_alpha   90.000
_cell_angle_beta   99.861
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   463.456
_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  0.864  0.118  0.275  1.0
  Ba  Ba1  1  0.364  0.382  0.775  1.0
  Ba  Ba2  1  0.136  0.882  0.725  1.0
  Ba  Ba3  1  0.636  0.618  0.225  1.0
  Ba  Ba4  1  0.334  0.038  0.262  1.0
  Ba  Ba5  1  0.834  0.462  0.762  1.0
  Ba  Ba6  1  0.666  0.962  0.738  1.0
  Ba  Ba7  1  0.166  0.538  0.238  1.0
  O  O8  1  0.632  0.929  0.364  1.0
  O  O9  1  0.132  0.571  0.864  1.0
  O  O10  1  0.368  0.071  0.636  1.0
  O  O11  1  0.868  0.429  0.136  1.0
  O  O12  1  0.065  0.839  0.332  1.0
  O  O13  1  0.565  0.661  0.832  1.0
  O  O14  1  0.935  0.161  0.668  1.0
  O  O15  1  0.435  0.339  0.168  1.0
  O  O16  1  0.937  0.863  0.026  1.0
  O  O17  1  0.437  0.637  0.526  1.0
  O  O18  1  0.063  0.137  0.974  1.0
  O  O19  1  0.563  0.363  0.474  1.0
  O  O20  1  0.346  0.739  0.026  1.0
  O  O21  1  0.846  0.761  0.526  1.0
  O  O22  1  0.654  0.261  0.974  1.0
  O  O23  1  0.154  0.239  0.474  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 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Ba site, Ba(2) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(1), two equivalent O(2), 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) and two equivalent Ba(2) atoms to form a mixture of corner and edge-sharing OBa4 tetrahedra. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to two equivalent Ba(1) and two equivalent Ba(2) atoms. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Ba(2) and two equivalent Ba(1) atoms. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to two equivalent Ba(1) and two equivalent Ba(2) atoms. is represented by the CIF card [CIF]
data_BaO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.348
_cell_length_b   7.955
_cell_length_c   7.084
_cell_angle_alpha   90.000
_cell_angle_beta   99.861
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   463.456
_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  0.864  0.118  0.275  1.0
  Ba  Ba1  1  0.364  0.382  0.775  1.0
  Ba  Ba2  1  0.136  0.882  0.725  1.0
  Ba  Ba3  1  0.636  0.618  0.225  1.0
  Ba  Ba4  1  0.334  0.038  0.262  1.0
  Ba  Ba5  1  0.834  0.462  0.762  1.0
  Ba  Ba6  1  0.666  0.962  0.738  1.0
  Ba  Ba7  1  0.166  0.538  0.238  1.0
  O  O8  1  0.632  0.929  0.364  1.0
  O  O9  1  0.132  0.571  0.864  1.0
  O  O10  1  0.368  0.071  0.636  1.0
  O  O11  1  0.868  0.429  0.136  1.0
  O  O12  1  0.065  0.839  0.332  1.0
  O  O13  1  0.565  0.661  0.832  1.0
  O  O14  1  0.935  0.161  0.668  1.0
  O  O15  1  0.435  0.339  0.168  1.0
  O  O16  1  0.937  0.863  0.026  1.0
  O  O17  1  0.437  0.637  0.526  1.0
  O  O18  1  0.063  0.137  0.974  1.0
  O  O19  1  0.563  0.363  0.474  1.0
  O  O20  1  0.346  0.739  0.026  1.0
  O  O21  1  0.846  0.761  0.526  1.0
  O  O22  1  0.654  0.261  0.974  1.0
  O  O23  1  0.154  0.239  0.474  1.0
[/CIF]
.