The compound described by MgSi2 crystallizes in the triclinic P1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to one Si(1), one Si(3), two equivalent Si(2), two equivalent Si(5), and two equivalent Si(8) atoms. In the second Mg site, Mg(2) is bonded in a 9-coordinate geometry to one Mg(3), one Si(2), one Si(5), two equivalent Si(1), two equivalent Si(4), and two equivalent Si(6) atoms. In the third Mg site, Mg(3) is bonded in a 4-coordinate geometry to one Mg(2), one Si(1), two equivalent Si(4), and two equivalent Si(7) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(3), one Si(4), one Si(8), and two equivalent Si(7) atoms. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(2), one Si(5), and two equivalent Si(6) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(2), two equivalent Mg(1), one Si(6), one Si(8), and two equivalent Si(5) atoms. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to one Mg(1), one Mg(4), one Si(5), one Si(7), and two equivalent Si(8) atoms. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(4), two equivalent Mg(2), two equivalent Mg(3), one Si(6), and one Si(7) atom. In the fifth Si site, Si(5) is bonded in a 7-coordinate geometry to one Mg(2), two equivalent Mg(1), one Si(1), one Si(3), and two equivalent Si(2) atoms. In the sixth Si site, Si(6) is bonded in a 6-coordinate geometry to two equivalent Mg(2), one Si(2), one Si(4), and two equivalent Si(1) atoms. In the seventh Si site, Si(7) is bonded in a 6-coordinate geometry to two equivalent Mg(3), two equivalent Mg(4), one Si(3), and one Si(4) atom. In the eighth Si site, Si(8) is bonded in a 6-coordinate geometry to one Mg(4), two equivalent Mg(1), one Si(2), and two equivalent Si(3) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.347
_cell_length_b   5.653
_cell_length_c   10.129
_cell_angle_alpha   100.791
_cell_angle_beta   97.945
_cell_angle_gamma   96.383
_symmetry_Int_Tables_number   1
_cell_volume   239.723
_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  0.107  0.894  0.815  1.0
  Mg  Mg1  1  0.125  0.650  0.178  1.0
  Mg  Mg2  1  0.560  0.378  0.350  1.0
  Mg  Mg3  1  0.518  0.977  0.557  1.0
  Si  Si4  1  0.155  0.169  0.087  1.0
  Si  Si5  1  0.585  0.589  0.920  1.0
  Si  Si6  1  0.981  0.389  0.662  1.0
  Si  Si7  1  0.705  0.834  0.307  1.0
  Si  Si8  1  0.059  0.386  0.905  1.0
  Si  Si9  1  0.634  0.959  0.091  1.0
  Si  Si10  1  0.053  0.174  0.445  1.0
  Si  Si11  1  0.519  0.602  0.683  1.0
[/CIF]
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The compound described by MgSi2 crystallizes in the triclinic P1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to one Si(1), one Si(3), two equivalent Si(2), two equivalent Si(5), and two equivalent Si(8) atoms. In the second Mg site, Mg(2) is bonded in a 9-coordinate geometry to one Mg(3), one Si(2), one Si(5), two equivalent Si(1), two equivalent Si(4), and two equivalent Si(6) atoms. In the third Mg site, Mg(3) is bonded in a 4-coordinate geometry to one Mg(2), one Si(1), two equivalent Si(4), and two equivalent Si(7) atoms. In the fourth Mg site, Mg(4) is bonded in a 5-coordinate geometry to one Si(3), one Si(4), one Si(8), and two equivalent Si(7) atoms. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), two equivalent Mg(2), one Si(5), and two equivalent Si(6) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(2), two equivalent Mg(1), one Si(6), one Si(8), and two equivalent Si(5) atoms. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to one Mg(1), one Mg(4), one Si(5), one Si(7), and two equivalent Si(8) atoms. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(4), two equivalent Mg(2), two equivalent Mg(3), one Si(6), and one Si(7) atom. In the fifth Si site, Si(5) is bonded in a 7-coordinate geometry to one Mg(2), two equivalent Mg(1), one Si(1), one Si(3), and two equivalent Si(2) atoms. In the sixth Si site, Si(6) is bonded in a 6-coordinate geometry to two equivalent Mg(2), one Si(2), one Si(4), and two equivalent Si(1) atoms. In the seventh Si site, Si(7) is bonded in a 6-coordinate geometry to two equivalent Mg(3), two equivalent Mg(4), one Si(3), and one Si(4) atom. In the eighth Si site, Si(8) is bonded in a 6-coordinate geometry to one Mg(4), two equivalent Mg(1), one Si(2), and two equivalent Si(3) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.347
_cell_length_b   5.653
_cell_length_c   10.129
_cell_angle_alpha   100.791
_cell_angle_beta   97.945
_cell_angle_gamma   96.383
_symmetry_Int_Tables_number   1
_cell_volume   239.723
_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  0.107  0.894  0.815  1.0
  Mg  Mg1  1  0.125  0.650  0.178  1.0
  Mg  Mg2  1  0.560  0.378  0.350  1.0
  Mg  Mg3  1  0.518  0.977  0.557  1.0
  Si  Si4  1  0.155  0.169  0.087  1.0
  Si  Si5  1  0.585  0.589  0.920  1.0
  Si  Si6  1  0.981  0.389  0.662  1.0
  Si  Si7  1  0.705  0.834  0.307  1.0
  Si  Si8  1  0.059  0.386  0.905  1.0
  Si  Si9  1  0.634  0.959  0.091  1.0
  Si  Si10  1  0.053  0.174  0.445  1.0
  Si  Si11  1  0.519  0.602  0.683  1.0
[/CIF]
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