The material structure described by MgSiO3 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, edges with three equivalent Mg(2)O6 octahedra, and  an edgeedge with one Si(2)O4 tetrahedra. In the second Mg site, Mg(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted MgO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra, and edges with three equivalent Mg(1)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-68°. In the second Si site, Si(2) is bonded to one O(1), one O(3), and two equivalent O(6) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-71°. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Mg(2), two equivalent Mg(1), and one Si(2) atom to form distorted corner-sharing OMg3Si trigonal pyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(2), two equivalent Mg(1), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(2), and one Si(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mg(2) and two equivalent Si(1) atoms. In the fifth O site, O(5) 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(6) is bonded in a trigonal non-coplanar geometry to one Mg(2) and two equivalent Si(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.061
_cell_length_b   5.263
_cell_length_c   9.380
_cell_angle_alpha   80.600
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   441.380
_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  0.156  0.415  0.281  1.0
  Mg  Mg1  1  0.344  0.915  0.281  1.0
  Mg  Mg2  1  0.491  0.579  0.768  1.0
  Mg  Mg3  1  0.844  0.585  0.719  1.0
  Mg  Mg4  1  0.656  0.085  0.719  1.0
  Mg  Mg5  1  0.509  0.421  0.232  1.0
  Mg  Mg6  1  0.991  0.921  0.232  1.0
  Mg  Mg7  1  0.009  0.079  0.768  1.0
  Si  Si8  1  0.666  0.824  0.431  1.0
  Si  Si9  1  0.713  0.805  0.981  1.0
  Si  Si10  1  0.334  0.176  0.569  1.0
  Si  Si11  1  0.213  0.695  0.019  1.0
  Si  Si12  1  0.787  0.305  0.981  1.0
  Si  Si13  1  0.287  0.195  0.019  1.0
  Si  Si14  1  0.834  0.324  0.431  1.0
  Si  Si15  1  0.166  0.676  0.569  1.0
  O  O16  1  0.670  0.359  0.846  1.0
  O  O17  1  0.343  0.224  0.392  1.0
  O  O18  1  0.556  0.832  0.898  1.0
  O  O19  1  0.188  0.350  0.618  1.0
  O  O20  1  0.330  0.641  0.154  1.0
  O  O21  1  0.843  0.277  0.608  1.0
  O  O22  1  0.029  0.776  0.652  1.0
  O  O23  1  0.944  0.332  0.898  1.0
  O  O24  1  0.471  0.276  0.652  1.0
  O  O25  1  0.688  0.150  0.382  1.0
  O  O26  1  0.268  0.482  0.913  1.0
  O  O27  1  0.830  0.859  0.846  1.0
  O  O28  1  0.312  0.850  0.618  1.0
  O  O29  1  0.812  0.650  0.382  1.0
  O  O30  1  0.732  0.518  0.087  1.0
  O  O31  1  0.971  0.224  0.348  1.0
  O  O32  1  0.657  0.776  0.608  1.0
  O  O33  1  0.157  0.724  0.392  1.0
  O  O34  1  0.056  0.668  0.102  1.0
  O  O35  1  0.170  0.141  0.154  1.0
  O  O36  1  0.768  0.018  0.087  1.0
  O  O37  1  0.232  0.982  0.913  1.0
  O  O38  1  0.529  0.724  0.348  1.0
  O  O39  1  0.444  0.168  0.102  1.0
[/CIF]
.
The material structure described by MgSiO3 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(3), one O(5), two equivalent O(1), and two equivalent O(2) atoms to form MgO6 octahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, edges with two equivalent Mg(1)O6 octahedra, edges with three equivalent Mg(2)O6 octahedra, and  an edgeedge with one Si(2)O4 tetrahedra. In the second Mg site, Mg(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted MgO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra, corners with four equivalent Si(2)O4 tetrahedra, and edges with three equivalent Mg(1)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-68°. In the second Si site, Si(2) is bonded to one O(1), one O(3), and two equivalent O(6) atoms to form SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with four equivalent Mg(2)O6 octahedra, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 37-71°. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Mg(2), two equivalent Mg(1), and one Si(2) atom to form distorted corner-sharing OMg3Si trigonal pyramids. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Mg(2), two equivalent Mg(1), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1), one Mg(2), and one Si(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Mg(2) and two equivalent Si(1) atoms. In the fifth O site, O(5) 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(6) is bonded in a trigonal non-coplanar geometry to one Mg(2) and two equivalent Si(2) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.061
_cell_length_b   5.263
_cell_length_c   9.380
_cell_angle_alpha   80.600
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   441.380
_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  0.156  0.415  0.281  1.0
  Mg  Mg1  1  0.344  0.915  0.281  1.0
  Mg  Mg2  1  0.491  0.579  0.768  1.0
  Mg  Mg3  1  0.844  0.585  0.719  1.0
  Mg  Mg4  1  0.656  0.085  0.719  1.0
  Mg  Mg5  1  0.509  0.421  0.232  1.0
  Mg  Mg6  1  0.991  0.921  0.232  1.0
  Mg  Mg7  1  0.009  0.079  0.768  1.0
  Si  Si8  1  0.666  0.824  0.431  1.0
  Si  Si9  1  0.713  0.805  0.981  1.0
  Si  Si10  1  0.334  0.176  0.569  1.0
  Si  Si11  1  0.213  0.695  0.019  1.0
  Si  Si12  1  0.787  0.305  0.981  1.0
  Si  Si13  1  0.287  0.195  0.019  1.0
  Si  Si14  1  0.834  0.324  0.431  1.0
  Si  Si15  1  0.166  0.676  0.569  1.0
  O  O16  1  0.670  0.359  0.846  1.0
  O  O17  1  0.343  0.224  0.392  1.0
  O  O18  1  0.556  0.832  0.898  1.0
  O  O19  1  0.188  0.350  0.618  1.0
  O  O20  1  0.330  0.641  0.154  1.0
  O  O21  1  0.843  0.277  0.608  1.0
  O  O22  1  0.029  0.776  0.652  1.0
  O  O23  1  0.944  0.332  0.898  1.0
  O  O24  1  0.471  0.276  0.652  1.0
  O  O25  1  0.688  0.150  0.382  1.0
  O  O26  1  0.268  0.482  0.913  1.0
  O  O27  1  0.830  0.859  0.846  1.0
  O  O28  1  0.312  0.850  0.618  1.0
  O  O29  1  0.812  0.650  0.382  1.0
  O  O30  1  0.732  0.518  0.087  1.0
  O  O31  1  0.971  0.224  0.348  1.0
  O  O32  1  0.657  0.776  0.608  1.0
  O  O33  1  0.157  0.724  0.392  1.0
  O  O34  1  0.056  0.668  0.102  1.0
  O  O35  1  0.170  0.141  0.154  1.0
  O  O36  1  0.768  0.018  0.087  1.0
  O  O37  1  0.232  0.982  0.913  1.0
  O  O38  1  0.529  0.724  0.348  1.0
  O  O39  1  0.444  0.168  0.102  1.0
[/CIF]
.