The structure described by MgSi2 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 10-coordinate geometry to one Si(3), one Si(6), two equivalent Si(1), three equivalent Si(2), and three equivalent Si(5) atoms. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to two equivalent Si(1), two equivalent Si(5), two equivalent Si(7), and three equivalent Si(6) atoms. In the third Mg site, Mg(3) is bonded in a 3-coordinate geometry to one Si(8), two equivalent Si(6), three equivalent Si(4), and three equivalent Si(7) atoms. In the fourth Mg site, Mg(4) is bonded to one Si(2), one Si(4), three equivalent Si(3), and three equivalent Si(8) atoms to form distorted edge-sharing MgSi8 hexagonal bipyramids. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), one Si(5), one Si(7), and two equivalent Si(6) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(4), three equivalent Mg(1), one Si(3), and two equivalent Si(5) atoms. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to one Mg(1), three equivalent Mg(4), one Si(2), and two equivalent Si(8) atoms. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(4), three equivalent Mg(3), one Si(8), and two equivalent Si(7) atoms. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent Mg(2), three equivalent Mg(1), one Si(1), one Si(6), and two equivalent Si(2) atoms. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to one Mg(1), two equivalent Mg(3), three equivalent Mg(2), one Si(5), and two equivalent Si(1) atoms. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to two equivalent Mg(2), three equivalent Mg(3), one Si(1), and two equivalent Si(4) atoms. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(3), three equivalent Mg(4), one Si(4), and two equivalent Si(3) atoms. is represented by the CIF file [CIF]
data_MgSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.874
_cell_length_b   5.419
_cell_length_c   11.588
_cell_angle_alpha   77.413
_cell_angle_beta   81.147
_cell_angle_gamma   69.432
_symmetry_Int_Tables_number   1
_cell_volume   221.491
_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  0.149  0.706  0.109  1.0
  Mg  Mg1  1  0.396  0.432  0.866  1.0
  Mg  Mg2  1  0.594  0.262  0.630  1.0
  Mg  Mg3  1  0.205  0.267  0.382  1.0
  Si  Si4  1  0.701  0.780  0.907  1.0
  Si  Si5  1  0.411  0.134  0.158  1.0
  Si  Si6  1  0.939  0.859  0.322  1.0
  Si  Si7  1  0.299  0.873  0.600  1.0
  Si  Si8  1  0.881  0.308  0.034  1.0
  Si  Si9  1  0.084  0.060  0.860  1.0
  Si  Si10  1  0.855  0.660  0.704  1.0
  Si  Si11  1  0.486  0.660  0.430  1.0
[/CIF]
.
The structure described by MgSi2 is Magnesium tetraboride-like structured and crystallizes in the triclinic P1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 10-coordinate geometry to one Si(3), one Si(6), two equivalent Si(1), three equivalent Si(2), and three equivalent Si(5) atoms. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to two equivalent Si(1), two equivalent Si(5), two equivalent Si(7), and three equivalent Si(6) atoms. In the third Mg site, Mg(3) is bonded in a 3-coordinate geometry to one Si(8), two equivalent Si(6), three equivalent Si(4), and three equivalent Si(7) atoms. In the fourth Mg site, Mg(4) is bonded to one Si(2), one Si(4), three equivalent Si(3), and three equivalent Si(8) atoms to form distorted edge-sharing MgSi8 hexagonal bipyramids. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a 8-coordinate geometry to two equivalent Mg(1), two equivalent Mg(2), one Si(5), one Si(7), and two equivalent Si(6) atoms. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(4), three equivalent Mg(1), one Si(3), and two equivalent Si(5) atoms. In the third Si site, Si(3) is bonded in a 6-coordinate geometry to one Mg(1), three equivalent Mg(4), one Si(2), and two equivalent Si(8) atoms. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(4), three equivalent Mg(3), one Si(8), and two equivalent Si(7) atoms. In the fifth Si site, Si(5) is bonded in a 9-coordinate geometry to two equivalent Mg(2), three equivalent Mg(1), one Si(1), one Si(6), and two equivalent Si(2) atoms. In the sixth Si site, Si(6) is bonded in a 9-coordinate geometry to one Mg(1), two equivalent Mg(3), three equivalent Mg(2), one Si(5), and two equivalent Si(1) atoms. In the seventh Si site, Si(7) is bonded in a 8-coordinate geometry to two equivalent Mg(2), three equivalent Mg(3), one Si(1), and two equivalent Si(4) atoms. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(3), three equivalent Mg(4), one Si(4), and two equivalent Si(3) atoms. is represented by the CIF file [CIF]
data_MgSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.874
_cell_length_b   5.419
_cell_length_c   11.588
_cell_angle_alpha   77.413
_cell_angle_beta   81.147
_cell_angle_gamma   69.432
_symmetry_Int_Tables_number   1
_cell_volume   221.491
_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  0.149  0.706  0.109  1.0
  Mg  Mg1  1  0.396  0.432  0.866  1.0
  Mg  Mg2  1  0.594  0.262  0.630  1.0
  Mg  Mg3  1  0.205  0.267  0.382  1.0
  Si  Si4  1  0.701  0.780  0.907  1.0
  Si  Si5  1  0.411  0.134  0.158  1.0
  Si  Si6  1  0.939  0.859  0.322  1.0
  Si  Si7  1  0.299  0.873  0.600  1.0
  Si  Si8  1  0.881  0.308  0.034  1.0
  Si  Si9  1  0.084  0.060  0.860  1.0
  Si  Si10  1  0.855  0.660  0.704  1.0
  Si  Si11  1  0.486  0.660  0.430  1.0
[/CIF]
.