The structure described by MgSi2 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to one Si(3), one Si(4), two equivalent Si(1), and three equivalent Si(2) atoms. In the second Mg site, Mg(2) is bonded to one Si(1), one Si(2), one Si(4), and three equivalent Si(3) atoms to form distorted MgSi6 octahedra that share corners with two equivalent Mg(2)Si6 octahedra, corners with three equivalent Si(1)Mg3Si3 octahedra, and edges with two equivalent Mg(2)Si6 octahedra. The corner-sharing octahedral tilt angles range from 52-96°. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one Mg(2), two equivalent Mg(1), one Si(4), and two equivalent Si(1) atoms to form distorted SiMg3Si3 octahedra that share corners with three equivalent Mg(2)Si6 octahedra and edges with two equivalent Si(1)Mg3Si3 octahedra. The corner-sharing octahedral tilt angles range from 52-83°. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(2), three equivalent Mg(1), one Si(3), and two equivalent Si(2) atoms. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to one Mg(1), three equivalent Mg(2), one Si(2), and two equivalent Si(3) atoms. In the fourth Si site, Si(4) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Si(1), and two equivalent Si(4) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.783
_cell_length_b   6.292
_cell_length_c   10.365
_cell_angle_alpha   73.826
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   236.926
_cell_formula_units_Z   4
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  0.230  0.184  0.761  1.0
  Mg  Mg1  1  0.225  0.343  0.247  1.0
  Mg  Mg2  1  0.725  0.657  0.753  1.0
  Mg  Mg3  1  0.730  0.816  0.239  1.0
  Si  Si4  1  0.239  0.589  0.435  1.0
  Si  Si5  1  0.704  0.938  0.950  1.0
  Si  Si6  1  0.228  0.445  0.948  1.0
  Si  Si7  1  0.865  0.037  0.560  1.0
  Si  Si8  1  0.365  0.963  0.440  1.0
  Si  Si9  1  0.728  0.555  0.052  1.0
  Si  Si10  1  0.204  0.062  0.050  1.0
  Si  Si11  1  0.739  0.411  0.565  1.0
[/CIF]
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The structure described by MgSi2 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to one Si(3), one Si(4), two equivalent Si(1), and three equivalent Si(2) atoms. In the second Mg site, Mg(2) is bonded to one Si(1), one Si(2), one Si(4), and three equivalent Si(3) atoms to form distorted MgSi6 octahedra that share corners with two equivalent Mg(2)Si6 octahedra, corners with three equivalent Si(1)Mg3Si3 octahedra, and edges with two equivalent Mg(2)Si6 octahedra. The corner-sharing octahedral tilt angles range from 52-96°. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one Mg(2), two equivalent Mg(1), one Si(4), and two equivalent Si(1) atoms to form distorted SiMg3Si3 octahedra that share corners with three equivalent Mg(2)Si6 octahedra and edges with two equivalent Si(1)Mg3Si3 octahedra. The corner-sharing octahedral tilt angles range from 52-83°. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(2), three equivalent Mg(1), one Si(3), and two equivalent Si(2) atoms. In the third Si site, Si(3) is bonded in a 7-coordinate geometry to one Mg(1), three equivalent Mg(2), one Si(2), and two equivalent Si(3) atoms. In the fourth Si site, Si(4) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Si(1), and two equivalent Si(4) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.783
_cell_length_b   6.292
_cell_length_c   10.365
_cell_angle_alpha   73.826
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   236.926
_cell_formula_units_Z   4
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  0.230  0.184  0.761  1.0
  Mg  Mg1  1  0.225  0.343  0.247  1.0
  Mg  Mg2  1  0.725  0.657  0.753  1.0
  Mg  Mg3  1  0.730  0.816  0.239  1.0
  Si  Si4  1  0.239  0.589  0.435  1.0
  Si  Si5  1  0.704  0.938  0.950  1.0
  Si  Si6  1  0.228  0.445  0.948  1.0
  Si  Si7  1  0.865  0.037  0.560  1.0
  Si  Si8  1  0.365  0.963  0.440  1.0
  Si  Si9  1  0.728  0.555  0.052  1.0
  Si  Si10  1  0.204  0.062  0.050  1.0
  Si  Si11  1  0.739  0.411  0.565  1.0
[/CIF]
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