The 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(1), one O(2), one O(4), and one O(6) atom to form distorted MgO4 tetrahedra that share  a cornercorner with one Mg(2)O4 tetrahedra and corners with three equivalent Si(1)O4 tetrahedra. In the second Mg site, Mg(2) is bonded to one O(1), one O(5), and two equivalent O(3) atoms to form MgO4 tetrahedra that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with two equivalent Mg(2)O4 tetrahedra, and corners with three equivalent Si(1)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O4 tetrahedra and corners with three equivalent Mg(2)O4 tetrahedra. In the second Si site, Si(2) is bonded in a trigonal planar geometry to one O(2), one O(5), and one O(6) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mg(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to two equivalent Mg(2) and one Si(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Mg(1) and one Si(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Mg(2) and one Si(2) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Mg(1) and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.213
_cell_length_b   11.408
_cell_length_c   7.794
_cell_angle_alpha   90.000
_cell_angle_beta   110.669
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   516.865
_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  0.919  0.958  0.730  1.0
  Mg  Mg1  1  0.593  0.816  0.358  1.0
  Mg  Mg2  1  0.581  0.458  0.270  1.0
  Mg  Mg3  1  0.081  0.042  0.270  1.0
  Mg  Mg4  1  0.407  0.184  0.642  1.0
  Mg  Mg5  1  0.093  0.684  0.358  1.0
  Mg  Mg6  1  0.907  0.316  0.642  1.0
  Mg  Mg7  1  0.419  0.542  0.730  1.0
  Si  Si8  1  0.168  0.396  0.382  1.0
  Si  Si9  1  0.691  0.876  0.001  1.0
  Si  Si10  1  0.309  0.124  0.999  1.0
  Si  Si11  1  0.332  0.896  0.618  1.0
  Si  Si12  1  0.832  0.604  0.618  1.0
  Si  Si13  1  0.668  0.104  0.382  1.0
  Si  Si14  1  0.191  0.624  0.001  1.0
  Si  Si15  1  0.809  0.376  0.999  1.0
  O  O16  1  0.223  0.530  0.465  1.0
  O  O17  1  0.615  0.901  0.781  1.0
  O  O18  1  0.666  0.193  0.547  1.0
  O  O19  1  0.385  0.099  0.219  1.0
  O  O20  1  0.115  0.599  0.781  1.0
  O  O21  1  0.332  0.358  0.274  1.0
  O  O22  1  0.514  0.844  0.094  1.0
  O  O23  1  0.885  0.401  0.219  1.0
  O  O24  1  0.668  0.642  0.726  1.0
  O  O25  1  0.450  0.593  0.109  1.0
  O  O26  1  0.723  0.970  0.465  1.0
  O  O27  1  0.168  0.858  0.726  1.0
  O  O28  1  0.777  0.470  0.535  1.0
  O  O29  1  0.014  0.656  0.094  1.0
  O  O30  1  0.834  0.693  0.453  1.0
  O  O31  1  0.832  0.142  0.274  1.0
  O  O32  1  0.166  0.307  0.547  1.0
  O  O33  1  0.050  0.093  0.891  1.0
  O  O34  1  0.486  0.156  0.906  1.0
  O  O35  1  0.277  0.030  0.535  1.0
  O  O36  1  0.550  0.407  0.891  1.0
  O  O37  1  0.334  0.807  0.453  1.0
  O  O38  1  0.986  0.344  0.906  1.0
  O  O39  1  0.950  0.907  0.109  1.0
[/CIF]
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The 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(1), one O(2), one O(4), and one O(6) atom to form distorted MgO4 tetrahedra that share  a cornercorner with one Mg(2)O4 tetrahedra and corners with three equivalent Si(1)O4 tetrahedra. In the second Mg site, Mg(2) is bonded to one O(1), one O(5), and two equivalent O(3) atoms to form MgO4 tetrahedra that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with two equivalent Mg(2)O4 tetrahedra, and corners with three equivalent Si(1)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with three equivalent Mg(1)O4 tetrahedra and corners with three equivalent Mg(2)O4 tetrahedra. In the second Si site, Si(2) is bonded in a trigonal planar geometry to one O(2), one O(5), and one O(6) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Mg(1), one Mg(2), and one Si(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Mg(1), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to two equivalent Mg(2) and one Si(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Mg(1) and one Si(1) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Mg(2) and one Si(2) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Mg(1) and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.213
_cell_length_b   11.408
_cell_length_c   7.794
_cell_angle_alpha   90.000
_cell_angle_beta   110.669
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   516.865
_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  0.919  0.958  0.730  1.0
  Mg  Mg1  1  0.593  0.816  0.358  1.0
  Mg  Mg2  1  0.581  0.458  0.270  1.0
  Mg  Mg3  1  0.081  0.042  0.270  1.0
  Mg  Mg4  1  0.407  0.184  0.642  1.0
  Mg  Mg5  1  0.093  0.684  0.358  1.0
  Mg  Mg6  1  0.907  0.316  0.642  1.0
  Mg  Mg7  1  0.419  0.542  0.730  1.0
  Si  Si8  1  0.168  0.396  0.382  1.0
  Si  Si9  1  0.691  0.876  0.001  1.0
  Si  Si10  1  0.309  0.124  0.999  1.0
  Si  Si11  1  0.332  0.896  0.618  1.0
  Si  Si12  1  0.832  0.604  0.618  1.0
  Si  Si13  1  0.668  0.104  0.382  1.0
  Si  Si14  1  0.191  0.624  0.001  1.0
  Si  Si15  1  0.809  0.376  0.999  1.0
  O  O16  1  0.223  0.530  0.465  1.0
  O  O17  1  0.615  0.901  0.781  1.0
  O  O18  1  0.666  0.193  0.547  1.0
  O  O19  1  0.385  0.099  0.219  1.0
  O  O20  1  0.115  0.599  0.781  1.0
  O  O21  1  0.332  0.358  0.274  1.0
  O  O22  1  0.514  0.844  0.094  1.0
  O  O23  1  0.885  0.401  0.219  1.0
  O  O24  1  0.668  0.642  0.726  1.0
  O  O25  1  0.450  0.593  0.109  1.0
  O  O26  1  0.723  0.970  0.465  1.0
  O  O27  1  0.168  0.858  0.726  1.0
  O  O28  1  0.777  0.470  0.535  1.0
  O  O29  1  0.014  0.656  0.094  1.0
  O  O30  1  0.834  0.693  0.453  1.0
  O  O31  1  0.832  0.142  0.274  1.0
  O  O32  1  0.166  0.307  0.547  1.0
  O  O33  1  0.050  0.093  0.891  1.0
  O  O34  1  0.486  0.156  0.906  1.0
  O  O35  1  0.277  0.030  0.535  1.0
  O  O36  1  0.550  0.407  0.891  1.0
  O  O37  1  0.334  0.807  0.453  1.0
  O  O38  1  0.986  0.344  0.906  1.0
  O  O39  1  0.950  0.907  0.109  1.0
[/CIF]
.