The structure described by MgSiO3 crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with three equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and edges with two equivalent Mg(1)O6 octahedra. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-61°. In the second Si site, Si(2) is bonded to one O(2), one O(4), and two equivalent O(6) atoms to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-59°. There are six inequivalent O sites. In the first O site, O(5) is bonded in a 2-coordinate geometry to one Mg(2) and two equivalent Si(1) atoms. In the second O site, O(6) is bonded in a 3-coordinate geometry to one Mg(2) and two equivalent Si(2) atoms. In the third O site, O(1) is bonded to one Mg(2), two equivalent Mg(1), and one Si(1) atom to form a mixture of distorted edge and corner-sharing OMg3Si trigonal pyramids. In the fourth O site, O(2) is bonded to one Mg(2), two equivalent Mg(1), and one Si(2) atom to form a mixture of distorted edge and corner-sharing OMg3Si trigonal pyramids. In the fifth O site, O(3) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the sixth O site, O(4) is bonded in a T-shaped geometry to one Mg(1), one Mg(2), and one Si(2) atom. is represented by the CIF card [CIF]
data_MgSiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.198
_cell_length_b   8.823
_cell_length_c   9.152
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   419.761
_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
  Mg  Mg0  1  0.781  0.847  0.003  1.0
  Mg  Mg1  1  0.219  0.153  0.503  1.0
  Mg  Mg2  1  0.719  0.347  0.503  1.0
  Mg  Mg3  1  0.281  0.653  0.003  1.0
  Mg  Mg4  1  0.281  0.009  0.997  1.0
  Mg  Mg5  1  0.719  0.991  0.497  1.0
  Mg  Mg6  1  0.219  0.509  0.497  1.0
  Mg  Mg7  1  0.781  0.491  0.997  1.0
  Si  Si8  1  0.629  0.661  0.299  1.0
  Si  Si9  1  0.371  0.339  0.799  1.0
  Si  Si10  1  0.871  0.161  0.799  1.0
  Si  Si11  1  0.129  0.839  0.299  1.0
  Si  Si12  1  0.431  0.838  0.703  1.0
  Si  Si13  1  0.569  0.162  0.203  1.0
  Si  Si14  1  0.069  0.338  0.203  1.0
  Si  Si15  1  0.931  0.662  0.703  1.0
  O  O16  1  0.618  0.659  0.121  1.0
  O  O17  1  0.382  0.341  0.621  1.0
  O  O18  1  0.882  0.159  0.621  1.0
  O  O19  1  0.118  0.841  0.121  1.0
  O  O20  1  0.440  0.837  0.880  1.0
  O  O21  1  0.560  0.163  0.380  1.0
  O  O22  1  0.060  0.337  0.380  1.0
  O  O23  1  0.940  0.663  0.880  1.0
  O  O24  1  0.539  0.509  0.379  1.0
  O  O25  1  0.461  0.491  0.879  1.0
  O  O26  1  0.961  0.009  0.879  1.0
  O  O27  1  0.039  0.991  0.379  1.0
  O  O28  1  0.398  0.996  0.623  1.0
  O  O29  1  0.602  0.004  0.123  1.0
  O  O30  1  0.102  0.496  0.123  1.0
  O  O31  1  0.898  0.504  0.623  1.0
  O  O32  1  0.924  0.705  0.354  1.0
  O  O33  1  0.076  0.295  0.854  1.0
  O  O34  1  0.576  0.205  0.854  1.0
  O  O35  1  0.424  0.795  0.354  1.0
  O  O36  1  0.222  0.712  0.643  1.0
  O  O37  1  0.778  0.288  0.143  1.0
  O  O38  1  0.278  0.212  0.143  1.0
  O  O39  1  0.722  0.788  0.643  1.0
[/CIF]
.
The structure described by MgSiO3 crystallizes in the orthorhombic Pna2_1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share corners with three equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and edges with two equivalent Mg(1)O6 octahedra. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-61°. In the second Si site, Si(2) is bonded to one O(2), one O(4), and two equivalent O(6) atoms to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-59°. There are six inequivalent O sites. In the first O site, O(5) is bonded in a 2-coordinate geometry to one Mg(2) and two equivalent Si(1) atoms. In the second O site, O(6) is bonded in a 3-coordinate geometry to one Mg(2) and two equivalent Si(2) atoms. In the third O site, O(1) is bonded to one Mg(2), two equivalent Mg(1), and one Si(1) atom to form a mixture of distorted edge and corner-sharing OMg3Si trigonal pyramids. In the fourth O site, O(2) is bonded to one Mg(2), two equivalent Mg(1), and one Si(2) atom to form a mixture of distorted edge and corner-sharing OMg3Si trigonal pyramids. In the fifth O site, O(3) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the sixth O site, O(4) is bonded in a T-shaped geometry to one Mg(1), one Mg(2), and one Si(2) atom. is represented by the CIF card [CIF]
data_MgSiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.198
_cell_length_b   8.823
_cell_length_c   9.152
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   419.761
_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
  Mg  Mg0  1  0.781  0.847  0.003  1.0
  Mg  Mg1  1  0.219  0.153  0.503  1.0
  Mg  Mg2  1  0.719  0.347  0.503  1.0
  Mg  Mg3  1  0.281  0.653  0.003  1.0
  Mg  Mg4  1  0.281  0.009  0.997  1.0
  Mg  Mg5  1  0.719  0.991  0.497  1.0
  Mg  Mg6  1  0.219  0.509  0.497  1.0
  Mg  Mg7  1  0.781  0.491  0.997  1.0
  Si  Si8  1  0.629  0.661  0.299  1.0
  Si  Si9  1  0.371  0.339  0.799  1.0
  Si  Si10  1  0.871  0.161  0.799  1.0
  Si  Si11  1  0.129  0.839  0.299  1.0
  Si  Si12  1  0.431  0.838  0.703  1.0
  Si  Si13  1  0.569  0.162  0.203  1.0
  Si  Si14  1  0.069  0.338  0.203  1.0
  Si  Si15  1  0.931  0.662  0.703  1.0
  O  O16  1  0.618  0.659  0.121  1.0
  O  O17  1  0.382  0.341  0.621  1.0
  O  O18  1  0.882  0.159  0.621  1.0
  O  O19  1  0.118  0.841  0.121  1.0
  O  O20  1  0.440  0.837  0.880  1.0
  O  O21  1  0.560  0.163  0.380  1.0
  O  O22  1  0.060  0.337  0.380  1.0
  O  O23  1  0.940  0.663  0.880  1.0
  O  O24  1  0.539  0.509  0.379  1.0
  O  O25  1  0.461  0.491  0.879  1.0
  O  O26  1  0.961  0.009  0.879  1.0
  O  O27  1  0.039  0.991  0.379  1.0
  O  O28  1  0.398  0.996  0.623  1.0
  O  O29  1  0.602  0.004  0.123  1.0
  O  O30  1  0.102  0.496  0.123  1.0
  O  O31  1  0.898  0.504  0.623  1.0
  O  O32  1  0.924  0.705  0.354  1.0
  O  O33  1  0.076  0.295  0.854  1.0
  O  O34  1  0.576  0.205  0.854  1.0
  O  O35  1  0.424  0.795  0.354  1.0
  O  O36  1  0.222  0.712  0.643  1.0
  O  O37  1  0.778  0.288  0.143  1.0
  O  O38  1  0.278  0.212  0.143  1.0
  O  O39  1  0.722  0.788  0.643  1.0
[/CIF]
.