The structure described by MgSi2 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to one Si(2), two equivalent Si(3), two equivalent Si(4), and three equivalent Si(1) atoms. In the second Mg site, Mg(2) is bonded in a 7-coordinate geometry to one Si(3), three equivalent Si(2), and three equivalent Si(4) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to three equivalent Mg(1), two equivalent Si(2), and three equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to one Mg(1), three equivalent Mg(2), two equivalent Si(1), two equivalent Si(3), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(2), two equivalent Mg(1), two equivalent Si(2), and three equivalent Si(1) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to two equivalent Mg(1), three equivalent Mg(2), two equivalent Si(2), 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   3.612
_cell_length_b   6.169
_cell_length_c   9.277
_cell_angle_alpha   84.828
_cell_angle_beta   89.146
_cell_angle_gamma   88.768
_symmetry_Int_Tables_number   1
_cell_volume   205.850
_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  0.747  0.446  0.208  1.0
  Mg  Mg1  1  0.253  0.554  0.792  1.0
  Mg  Mg2  1  0.750  0.853  0.591  1.0
  Mg  Mg3  1  0.250  0.147  0.409  1.0
  Si  Si4  1  0.779  0.245  0.937  1.0
  Si  Si5  1  0.221  0.755  0.063  1.0
  Si  Si6  1  0.753  0.861  0.282  1.0
  Si  Si7  1  0.247  0.139  0.718  1.0
  Si  Si8  1  0.274  0.127  0.118  1.0
  Si  Si9  1  0.726  0.873  0.882  1.0
  Si  Si10  1  0.747  0.373  0.568  1.0
  Si  Si11  1  0.253  0.627  0.432  1.0
[/CIF]
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The structure described by MgSi2 crystallizes in the triclinic P-1 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to one Si(2), two equivalent Si(3), two equivalent Si(4), and three equivalent Si(1) atoms. In the second Mg site, Mg(2) is bonded in a 7-coordinate geometry to one Si(3), three equivalent Si(2), and three equivalent Si(4) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to three equivalent Mg(1), two equivalent Si(2), and three equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to one Mg(1), three equivalent Mg(2), two equivalent Si(1), two equivalent Si(3), and two equivalent Si(4) atoms. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(2), two equivalent Mg(1), two equivalent Si(2), and three equivalent Si(1) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to two equivalent Mg(1), three equivalent Mg(2), two equivalent Si(2), 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   3.612
_cell_length_b   6.169
_cell_length_c   9.277
_cell_angle_alpha   84.828
_cell_angle_beta   89.146
_cell_angle_gamma   88.768
_symmetry_Int_Tables_number   1
_cell_volume   205.850
_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  0.747  0.446  0.208  1.0
  Mg  Mg1  1  0.253  0.554  0.792  1.0
  Mg  Mg2  1  0.750  0.853  0.591  1.0
  Mg  Mg3  1  0.250  0.147  0.409  1.0
  Si  Si4  1  0.779  0.245  0.937  1.0
  Si  Si5  1  0.221  0.755  0.063  1.0
  Si  Si6  1  0.753  0.861  0.282  1.0
  Si  Si7  1  0.247  0.139  0.718  1.0
  Si  Si8  1  0.274  0.127  0.118  1.0
  Si  Si9  1  0.726  0.873  0.882  1.0
  Si  Si10  1  0.747  0.373  0.568  1.0
  Si  Si11  1  0.253  0.627  0.432  1.0
[/CIF]
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