The compound described by MgO crystallizes in the monoclinic C2/c space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form a mixture of corner and edge-sharing MgO4 trigonal pyramids. In the second Mg site, Mg(2) is bonded in a distorted see-saw-like geometry to one O(3) and three equivalent O(1) atoms. In the third Mg site, Mg(3) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing MgO4 trigonal pyramids. There are three inequivalent O sites. In the first O site, O(3) is bonded to one Mg(2), one Mg(3), and two equivalent Mg(1) atoms to form a mixture of corner and edge-sharing OMg4 trigonal pyramids. In the second O site, O(1) is bonded in a distorted see-saw-like geometry to one Mg(3) and three equivalent Mg(2) atoms. In the third O site, O(2) is bonded to two equivalent Mg(1) and two equivalent Mg(3) atoms to form a mixture of corner and edge-sharing OMg4 trigonal pyramids. is represented by the CIF file [CIF]
data_MgO
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.734
_cell_length_b   8.734
_cell_length_c   5.680
_cell_angle_alpha   89.771
_cell_angle_beta   89.771
_cell_angle_gamma   59.928
_symmetry_Int_Tables_number   1
_cell_volume   374.979
_cell_formula_units_Z   12
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
  Mg  Mg0  1  0.177  0.381  0.423  1.0
  Mg  Mg1  1  0.619  0.823  0.077  1.0
  Mg  Mg2  1  0.823  0.619  0.577  1.0
  Mg  Mg3  1  0.381  0.177  0.923  1.0
  Mg  Mg4  1  0.038  0.830  0.425  1.0
  Mg  Mg5  1  0.170  0.962  0.075  1.0
  Mg  Mg6  1  0.962  0.170  0.575  1.0
  Mg  Mg7  1  0.830  0.038  0.925  1.0
  Mg  Mg8  1  0.059  0.616  0.923  1.0
  Mg  Mg9  1  0.384  0.941  0.577  1.0
  Mg  Mg10  1  0.941  0.384  0.077  1.0
  Mg  Mg11  1  0.616  0.059  0.423  1.0
  O  O12  1  0.041  0.825  0.071  1.0
  O  O13  1  0.175  0.959  0.429  1.0
  O  O14  1  0.959  0.175  0.929  1.0
  O  O15  1  0.825  0.041  0.571  1.0
  O  O16  1  0.182  0.379  0.073  1.0
  O  O17  1  0.621  0.818  0.427  1.0
  O  O18  1  0.818  0.621  0.927  1.0
  O  O19  1  0.379  0.182  0.573  1.0
  O  O20  1  0.064  0.617  0.573  1.0
  O  O21  1  0.383  0.936  0.927  1.0
  O  O22  1  0.936  0.383  0.427  1.0
  O  O23  1  0.617  0.064  0.073  1.0
[/CIF]
.
The compound described by MgO crystallizes in the monoclinic C2/c space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form a mixture of corner and edge-sharing MgO4 trigonal pyramids. In the second Mg site, Mg(2) is bonded in a distorted see-saw-like geometry to one O(3) and three equivalent O(1) atoms. In the third Mg site, Mg(3) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form a mixture of corner and edge-sharing MgO4 trigonal pyramids. There are three inequivalent O sites. In the first O site, O(3) is bonded to one Mg(2), one Mg(3), and two equivalent Mg(1) atoms to form a mixture of corner and edge-sharing OMg4 trigonal pyramids. In the second O site, O(1) is bonded in a distorted see-saw-like geometry to one Mg(3) and three equivalent Mg(2) atoms. In the third O site, O(2) is bonded to two equivalent Mg(1) and two equivalent Mg(3) atoms to form a mixture of corner and edge-sharing OMg4 trigonal pyramids. is represented by the CIF file [CIF]
data_MgO
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.734
_cell_length_b   8.734
_cell_length_c   5.680
_cell_angle_alpha   89.771
_cell_angle_beta   89.771
_cell_angle_gamma   59.928
_symmetry_Int_Tables_number   1
_cell_volume   374.979
_cell_formula_units_Z   12
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
  Mg  Mg0  1  0.177  0.381  0.423  1.0
  Mg  Mg1  1  0.619  0.823  0.077  1.0
  Mg  Mg2  1  0.823  0.619  0.577  1.0
  Mg  Mg3  1  0.381  0.177  0.923  1.0
  Mg  Mg4  1  0.038  0.830  0.425  1.0
  Mg  Mg5  1  0.170  0.962  0.075  1.0
  Mg  Mg6  1  0.962  0.170  0.575  1.0
  Mg  Mg7  1  0.830  0.038  0.925  1.0
  Mg  Mg8  1  0.059  0.616  0.923  1.0
  Mg  Mg9  1  0.384  0.941  0.577  1.0
  Mg  Mg10  1  0.941  0.384  0.077  1.0
  Mg  Mg11  1  0.616  0.059  0.423  1.0
  O  O12  1  0.041  0.825  0.071  1.0
  O  O13  1  0.175  0.959  0.429  1.0
  O  O14  1  0.959  0.175  0.929  1.0
  O  O15  1  0.825  0.041  0.571  1.0
  O  O16  1  0.182  0.379  0.073  1.0
  O  O17  1  0.621  0.818  0.427  1.0
  O  O18  1  0.818  0.621  0.927  1.0
  O  O19  1  0.379  0.182  0.573  1.0
  O  O20  1  0.064  0.617  0.573  1.0
  O  O21  1  0.383  0.936  0.927  1.0
  O  O22  1  0.936  0.383  0.427  1.0
  O  O23  1  0.617  0.064  0.073  1.0
[/CIF]
.