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(2), one O(6), two equivalent O(1), and two equivalent O(4) atoms to form distorted MgO6 octahedra that share corners with three equivalent Mg(2)O6 octahedra, corners with two equivalent Si(2)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Si(1)O5 trigonal bipyramid, edges with two equivalent Si(2)O5 trigonal bipyramids, and  a faceface with one Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-29°. In the second Mg site, Mg(2) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with two equivalent Si(1)O5 trigonal bipyramids, edges with two equivalent Mg(2)O6 octahedra,  an edgeedge with one Si(2)O5 trigonal bipyramid, edges with two equivalent Si(1)O5 trigonal bipyramids, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-29°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), one O(6), and two equivalent O(3) atoms to form SiO5 trigonal bipyramids that share corners with two equivalent Mg(2)O6 octahedra,  a cornercorner with one Si(2)O5 trigonal bipyramid, corners with two equivalent Si(1)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and  an edgeedge with one Si(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 33-39°. In the second Si site, Si(2) is bonded to one O(2), one O(5), one O(6), and two equivalent O(4) atoms to form distorted SiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O6 octahedra,  a cornercorner with one Si(1)O5 trigonal bipyramid, corners with two equivalent Si(2)O5 trigonal bipyramids,  an edgeedge with one Mg(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and  an edgeedge with one Si(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 31-37°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Mg(2) atoms. In the second O site, O(2) is bonded in a square co-planar geometry to one Mg(1), one Mg(2), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(2) and two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1) and two equivalent Si(2) atoms to form distorted edge-sharing OMg2Si2 trigonal pyramids. In the fifth O site, O(5) is bonded in an L-shaped geometry to one Si(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Mg(1), one Mg(2), one Si(1), and one Si(2) atom. is represented by the CIF file [CIF]
data_MgSiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.816
_cell_length_b   8.826
_cell_length_c   9.592
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   407.755
_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  0.730  0.665  0.754  1.0
  Mg  Mg1  1  0.726  0.664  0.498  1.0
  Mg  Mg2  1  0.270  0.335  0.254  1.0
  Mg  Mg3  1  0.770  0.165  0.254  1.0
  Mg  Mg4  1  0.274  0.336  0.998  1.0
  Mg  Mg5  1  0.774  0.164  0.998  1.0
  Mg  Mg6  1  0.230  0.835  0.754  1.0
  Mg  Mg7  1  0.226  0.836  0.498  1.0
  Si  Si8  1  0.911  0.359  0.758  1.0
  Si  Si9  1  0.589  0.859  0.258  1.0
  Si  Si10  1  0.411  0.141  0.758  1.0
  Si  Si11  1  0.089  0.641  0.258  1.0
  Si  Si12  1  0.892  0.356  0.493  1.0
  Si  Si13  1  0.608  0.856  0.993  1.0
  Si  Si14  1  0.392  0.144  0.493  1.0
  Si  Si15  1  0.108  0.644  0.993  1.0
  O  O16  1  0.466  0.204  0.125  1.0
  O  O17  1  0.991  0.499  0.375  1.0
  O  O18  1  0.009  0.501  0.875  1.0
  O  O19  1  0.034  0.704  0.625  1.0
  O  O20  1  0.892  0.792  0.341  1.0
  O  O21  1  0.534  0.796  0.625  1.0
  O  O22  1  0.491  0.001  0.375  1.0
  O  O23  1  0.392  0.708  0.341  1.0
  O  O24  1  0.586  0.295  0.408  1.0
  O  O25  1  0.863  0.659  0.122  1.0
  O  O26  1  0.914  0.795  0.908  1.0
  O  O27  1  0.108  0.208  0.841  1.0
  O  O28  1  0.086  0.205  0.408  1.0
  O  O29  1  0.414  0.705  0.908  1.0
  O  O30  1  0.214  0.042  0.627  1.0
  O  O31  1  0.363  0.841  0.122  1.0
  O  O32  1  0.966  0.296  0.125  1.0
  O  O33  1  0.509  0.999  0.875  1.0
  O  O34  1  0.786  0.958  0.127  1.0
  O  O35  1  0.637  0.159  0.622  1.0
  O  O36  1  0.608  0.292  0.841  1.0
  O  O37  1  0.286  0.542  0.127  1.0
  O  O38  1  0.137  0.341  0.622  1.0
  O  O39  1  0.714  0.458  0.627  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(2), one O(6), two equivalent O(1), and two equivalent O(4) atoms to form distorted MgO6 octahedra that share corners with three equivalent Mg(2)O6 octahedra, corners with two equivalent Si(2)O5 trigonal bipyramids, edges with two equivalent Mg(1)O6 octahedra,  an edgeedge with one Si(1)O5 trigonal bipyramid, edges with two equivalent Si(2)O5 trigonal bipyramids, and  a faceface with one Mg(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-29°. In the second Mg site, Mg(2) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with two equivalent Si(1)O5 trigonal bipyramids, edges with two equivalent Mg(2)O6 octahedra,  an edgeedge with one Si(2)O5 trigonal bipyramid, edges with two equivalent Si(1)O5 trigonal bipyramids, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 2-29°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(5), one O(6), and two equivalent O(3) atoms to form SiO5 trigonal bipyramids that share corners with two equivalent Mg(2)O6 octahedra,  a cornercorner with one Si(2)O5 trigonal bipyramid, corners with two equivalent Si(1)O5 trigonal bipyramids,  an edgeedge with one Mg(1)O6 octahedra, edges with two equivalent Mg(2)O6 octahedra, and  an edgeedge with one Si(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 33-39°. In the second Si site, Si(2) is bonded to one O(2), one O(5), one O(6), and two equivalent O(4) atoms to form distorted SiO5 trigonal bipyramids that share corners with two equivalent Mg(1)O6 octahedra,  a cornercorner with one Si(1)O5 trigonal bipyramid, corners with two equivalent Si(2)O5 trigonal bipyramids,  an edgeedge with one Mg(2)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and  an edgeedge with one Si(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 31-37°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(1) and two equivalent Mg(2) atoms. In the second O site, O(2) is bonded in a square co-planar geometry to one Mg(1), one Mg(2), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg(2) and two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Mg(1) and two equivalent Si(2) atoms to form distorted edge-sharing OMg2Si2 trigonal pyramids. In the fifth O site, O(5) is bonded in an L-shaped geometry to one Si(1) and one Si(2) atom. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Mg(1), one Mg(2), one Si(1), and one Si(2) atom. is represented by the CIF file [CIF]
data_MgSiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.816
_cell_length_b   8.826
_cell_length_c   9.592
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   407.755
_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  0.730  0.665  0.754  1.0
  Mg  Mg1  1  0.726  0.664  0.498  1.0
  Mg  Mg2  1  0.270  0.335  0.254  1.0
  Mg  Mg3  1  0.770  0.165  0.254  1.0
  Mg  Mg4  1  0.274  0.336  0.998  1.0
  Mg  Mg5  1  0.774  0.164  0.998  1.0
  Mg  Mg6  1  0.230  0.835  0.754  1.0
  Mg  Mg7  1  0.226  0.836  0.498  1.0
  Si  Si8  1  0.911  0.359  0.758  1.0
  Si  Si9  1  0.589  0.859  0.258  1.0
  Si  Si10  1  0.411  0.141  0.758  1.0
  Si  Si11  1  0.089  0.641  0.258  1.0
  Si  Si12  1  0.892  0.356  0.493  1.0
  Si  Si13  1  0.608  0.856  0.993  1.0
  Si  Si14  1  0.392  0.144  0.493  1.0
  Si  Si15  1  0.108  0.644  0.993  1.0
  O  O16  1  0.466  0.204  0.125  1.0
  O  O17  1  0.991  0.499  0.375  1.0
  O  O18  1  0.009  0.501  0.875  1.0
  O  O19  1  0.034  0.704  0.625  1.0
  O  O20  1  0.892  0.792  0.341  1.0
  O  O21  1  0.534  0.796  0.625  1.0
  O  O22  1  0.491  0.001  0.375  1.0
  O  O23  1  0.392  0.708  0.341  1.0
  O  O24  1  0.586  0.295  0.408  1.0
  O  O25  1  0.863  0.659  0.122  1.0
  O  O26  1  0.914  0.795  0.908  1.0
  O  O27  1  0.108  0.208  0.841  1.0
  O  O28  1  0.086  0.205  0.408  1.0
  O  O29  1  0.414  0.705  0.908  1.0
  O  O30  1  0.214  0.042  0.627  1.0
  O  O31  1  0.363  0.841  0.122  1.0
  O  O32  1  0.966  0.296  0.125  1.0
  O  O33  1  0.509  0.999  0.875  1.0
  O  O34  1  0.786  0.958  0.127  1.0
  O  O35  1  0.637  0.159  0.622  1.0
  O  O36  1  0.608  0.292  0.841  1.0
  O  O37  1  0.286  0.542  0.127  1.0
  O  O38  1  0.137  0.341  0.622  1.0
  O  O39  1  0.714  0.458  0.627  1.0
[/CIF]
.