The material described by MgSi2 crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to one Si(1), one Si(10), one Si(11), one Si(13), one Si(4), one Si(5), one Si(6), and one Si(7) atom. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to one Si(10), one Si(12), one Si(14), one Si(16), one Si(2), one Si(4), one Si(6), and one Si(8) atom. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Si(13), one Si(2), one Si(3), one Si(5), one Si(7), and one Si(9) atom. In the fourth Mg site, Mg(4) is bonded in a 8-coordinate geometry to one Si(1), one Si(10), one Si(12), one Si(15), one Si(16), one Si(4), one Si(6), and one Si(8) atom. In the fifth Mg site, Mg(5) is bonded in a 6-coordinate geometry to one Si(14), one Si(15), one Si(2), one Si(3), one Si(5), one Si(7), and one Si(9) atom. In the sixth Mg site, Mg(6) is bonded in a 8-coordinate geometry to one Si(12), one Si(14), one Si(15), one Si(16), one Si(3), one Si(6), one Si(8), and one Si(9) atom. In the seventh Mg site, Mg(7) is bonded in a 5-coordinate geometry to one Si(11), one Si(3), one Si(5), one Si(7), and one Si(9) atom. In the eighth Mg site, Mg(8) is bonded in a 5-coordinate geometry to one Si(13), one Si(14), one Si(2), one Si(5), and one Si(9) atom. There are sixteen inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted hexagonal planar geometry to one Mg(1), one Mg(4), one Si(10), one Si(16), one Si(4), and one Si(5) atom. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(3), one Mg(5), one Mg(8), one Si(14), one Si(15), and one Si(8) atom. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(5), one Mg(6), one Mg(7), one Si(12), one Si(14), one Si(15), and one Si(9) atom. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), one Si(1), one Si(10), one Si(6), and one Si(8) atom. In the fifth Si site, Si(5) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), one Mg(5), one Mg(7), one Mg(8), one Si(1), and one Si(13) atom. In the sixth Si site, Si(6) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), one Mg(6), one Si(11), one Si(16), and one Si(4) atom. In the seventh Si site, Si(7) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), one Mg(5), one Mg(7), one Si(10), one Si(11), and one Si(16) atom. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(4), one Mg(6), one Si(12), one Si(15), one Si(2), and one Si(4) atom. In the ninth Si site, Si(9) is bonded in a 7-coordinate geometry to one Mg(3), one Mg(5), one Mg(6), one Mg(7), one Mg(8), one Si(15), and one Si(3) atom. In the tenth Si site, Si(10) is bonded in a distorted hexagonal pyramidal geometry to one Mg(1), one Mg(2), one Mg(4), one Si(1), one Si(13), one Si(4), and one Si(7) atom. In the eleventh Si site, Si(11) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(7), one Si(13), one Si(6), and one Si(7) atom. In the twelfth Si site, Si(12) is bonded in a 6-coordinate geometry to one Mg(2), one Mg(4), one Mg(6), one Si(14), one Si(3), and one Si(8) atom. In the thirteenth Si site, Si(13) is bonded in a 6-coordinate geometry to one Mg(1), one Mg(3), one Mg(8), one Si(10), one Si(11), and one Si(5) atom. In the fourteenth Si site, Si(14) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(5), one Mg(6), one Mg(8), one Si(12), one Si(2), and one Si(3) atom. In the fifteenth Si site, Si(15) is bonded in a 6-coordinate geometry to one Mg(4), one Mg(5), one Mg(6), one Si(2), one Si(3), one Si(8), and one Si(9) atom. In the sixteenth Si site, Si(16) is bonded in a 6-coordinate geometry to one Mg(2), one Mg(4), one Mg(6), one Si(1), one Si(6), and one Si(7) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.921
_cell_length_b   6.747
_cell_length_c   11.514
_cell_angle_alpha   77.112
_cell_angle_beta   85.278
_cell_angle_gamma   86.042
_symmetry_Int_Tables_number   1
_cell_volume   446.220
_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  0.258  0.175  0.130  1.0
  Mg  Mg1  1  0.746  0.182  0.768  1.0
  Mg  Mg2  1  0.651  0.662  0.356  1.0
  Mg  Mg3  1  0.670  0.724  0.817  1.0
  Mg  Mg4  1  0.853  0.114  0.356  1.0
  Mg  Mg5  1  0.163  0.935  0.681  1.0
  Mg  Mg6  1  0.143  0.762  0.261  1.0
  Mg  Mg7  1  0.305  0.312  0.372  1.0
  Si  Si8  1  0.032  0.528  0.982  1.0
  Si  Si9  1  0.607  0.313  0.540  1.0
  Si  Si10  1  0.957  0.726  0.511  1.0
  Si  Si11  1  0.367  0.361  0.886  1.0
  Si  Si12  1  0.959  0.462  0.201  1.0
  Si  Si13  1  0.345  0.995  0.898  1.0
  Si  Si14  1  0.803  0.995  0.121  1.0
  Si  Si15  1  0.447  0.533  0.675  1.0
  Si  Si16  1  0.305  0.901  0.437  1.0
  Si  Si17  1  0.703  0.326  0.002  1.0
  Si  Si18  1  0.479  0.833  0.087  1.0
  Si  Si19  1  0.043  0.522  0.711  1.0
  Si  Si20  1  0.560  0.474  0.168  1.0
  Si  Si21  1  0.007  0.333  0.558  1.0
  Si  Si22  1  0.611  0.935  0.571  1.0
  Si  Si23  1  0.966  0.897  0.940  1.0
[/CIF]
.
The material described by MgSi2 crystallizes in the triclinic P1 space group. There are eight inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 7-coordinate geometry to one Si(1), one Si(10), one Si(11), one Si(13), one Si(4), one Si(5), one Si(6), and one Si(7) atom. In the second Mg site, Mg(2) is bonded in a 8-coordinate geometry to one Si(10), one Si(12), one Si(14), one Si(16), one Si(2), one Si(4), one Si(6), and one Si(8) atom. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to one Si(13), one Si(2), one Si(3), one Si(5), one Si(7), and one Si(9) atom. In the fourth Mg site, Mg(4) is bonded in a 8-coordinate geometry to one Si(1), one Si(10), one Si(12), one Si(15), one Si(16), one Si(4), one Si(6), and one Si(8) atom. In the fifth Mg site, Mg(5) is bonded in a 6-coordinate geometry to one Si(14), one Si(15), one Si(2), one Si(3), one Si(5), one Si(7), and one Si(9) atom. In the sixth Mg site, Mg(6) is bonded in a 8-coordinate geometry to one Si(12), one Si(14), one Si(15), one Si(16), one Si(3), one Si(6), one Si(8), and one Si(9) atom. In the seventh Mg site, Mg(7) is bonded in a 5-coordinate geometry to one Si(11), one Si(3), one Si(5), one Si(7), and one Si(9) atom. In the eighth Mg site, Mg(8) is bonded in a 5-coordinate geometry to one Si(13), one Si(14), one Si(2), one Si(5), and one Si(9) atom. There are sixteen inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted hexagonal planar geometry to one Mg(1), one Mg(4), one Si(10), one Si(16), one Si(4), and one Si(5) atom. In the second Si site, Si(2) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(3), one Mg(5), one Mg(8), one Si(14), one Si(15), and one Si(8) atom. In the third Si site, Si(3) is bonded in a 8-coordinate geometry to one Mg(3), one Mg(5), one Mg(6), one Mg(7), one Si(12), one Si(14), one Si(15), and one Si(9) atom. In the fourth Si site, Si(4) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), one Si(1), one Si(10), one Si(6), and one Si(8) atom. In the fifth Si site, Si(5) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), one Mg(5), one Mg(7), one Mg(8), one Si(1), and one Si(13) atom. In the sixth Si site, Si(6) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), one Mg(6), one Si(11), one Si(16), and one Si(4) atom. In the seventh Si site, Si(7) is bonded in a 7-coordinate geometry to one Mg(1), one Mg(3), one Mg(5), one Mg(7), one Si(10), one Si(11), and one Si(16) atom. In the eighth Si site, Si(8) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(4), one Mg(6), one Si(12), one Si(15), one Si(2), and one Si(4) atom. In the ninth Si site, Si(9) is bonded in a 7-coordinate geometry to one Mg(3), one Mg(5), one Mg(6), one Mg(7), one Mg(8), one Si(15), and one Si(3) atom. In the tenth Si site, Si(10) is bonded in a distorted hexagonal pyramidal geometry to one Mg(1), one Mg(2), one Mg(4), one Si(1), one Si(13), one Si(4), and one Si(7) atom. In the eleventh Si site, Si(11) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(7), one Si(13), one Si(6), and one Si(7) atom. In the twelfth Si site, Si(12) is bonded in a 6-coordinate geometry to one Mg(2), one Mg(4), one Mg(6), one Si(14), one Si(3), and one Si(8) atom. In the thirteenth Si site, Si(13) is bonded in a 6-coordinate geometry to one Mg(1), one Mg(3), one Mg(8), one Si(10), one Si(11), and one Si(5) atom. In the fourteenth Si site, Si(14) is bonded in a 7-coordinate geometry to one Mg(2), one Mg(5), one Mg(6), one Mg(8), one Si(12), one Si(2), and one Si(3) atom. In the fifteenth Si site, Si(15) is bonded in a 6-coordinate geometry to one Mg(4), one Mg(5), one Mg(6), one Si(2), one Si(3), one Si(8), and one Si(9) atom. In the sixteenth Si site, Si(16) is bonded in a 6-coordinate geometry to one Mg(2), one Mg(4), one Mg(6), one Si(1), one Si(6), and one Si(7) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSi2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.921
_cell_length_b   6.747
_cell_length_c   11.514
_cell_angle_alpha   77.112
_cell_angle_beta   85.278
_cell_angle_gamma   86.042
_symmetry_Int_Tables_number   1
_cell_volume   446.220
_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  0.258  0.175  0.130  1.0
  Mg  Mg1  1  0.746  0.182  0.768  1.0
  Mg  Mg2  1  0.651  0.662  0.356  1.0
  Mg  Mg3  1  0.670  0.724  0.817  1.0
  Mg  Mg4  1  0.853  0.114  0.356  1.0
  Mg  Mg5  1  0.163  0.935  0.681  1.0
  Mg  Mg6  1  0.143  0.762  0.261  1.0
  Mg  Mg7  1  0.305  0.312  0.372  1.0
  Si  Si8  1  0.032  0.528  0.982  1.0
  Si  Si9  1  0.607  0.313  0.540  1.0
  Si  Si10  1  0.957  0.726  0.511  1.0
  Si  Si11  1  0.367  0.361  0.886  1.0
  Si  Si12  1  0.959  0.462  0.201  1.0
  Si  Si13  1  0.345  0.995  0.898  1.0
  Si  Si14  1  0.803  0.995  0.121  1.0
  Si  Si15  1  0.447  0.533  0.675  1.0
  Si  Si16  1  0.305  0.901  0.437  1.0
  Si  Si17  1  0.703  0.326  0.002  1.0
  Si  Si18  1  0.479  0.833  0.087  1.0
  Si  Si19  1  0.043  0.522  0.711  1.0
  Si  Si20  1  0.560  0.474  0.168  1.0
  Si  Si21  1  0.007  0.333  0.558  1.0
  Si  Si22  1  0.611  0.935  0.571  1.0
  Si  Si23  1  0.966  0.897  0.940  1.0
[/CIF]
.