The compound described by Mg2Si crystallizes in the monoclinic P2_1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 4-coordinate geometry to two equivalent Si(1) and two equivalent Si(2) atoms. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to one Si(2) and three equivalent Si(1) atoms. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to two equivalent Si(1) and three equivalent Si(2) atoms. In the fourth Mg site, Mg(4) is bonded in a distorted water-like geometry to one Si(2) and two equivalent Si(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(4), three equivalent Mg(2), and one Si(2) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(4), two equivalent Mg(1), three equivalent Mg(3), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.492
_cell_length_b   5.165
_cell_length_c   8.455
_cell_angle_alpha   78.576
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   235.076
_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  0.908  0.054  0.713  1.0
  Mg  Mg1  1  0.186  0.495  0.122  1.0
  Mg  Mg2  1  0.686  0.505  0.878  1.0
  Mg  Mg3  1  0.399  0.348  0.508  1.0
  Mg  Mg4  1  0.408  0.946  0.287  1.0
  Mg  Mg5  1  0.386  0.004  0.905  1.0
  Mg  Mg6  1  0.886  0.996  0.095  1.0
  Mg  Mg7  1  0.899  0.652  0.492  1.0
  Si  Si8  1  0.170  0.508  0.792  1.0
  Si  Si9  1  0.951  0.189  0.382  1.0
  Si  Si10  1  0.451  0.811  0.618  1.0
  Si  Si11  1  0.670  0.492  0.208  1.0
[/CIF]
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The compound described by Mg2Si crystallizes in the monoclinic P2_1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 4-coordinate geometry to two equivalent Si(1) and two equivalent Si(2) atoms. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to one Si(2) and three equivalent Si(1) atoms. In the third Mg site, Mg(3) is bonded in a 5-coordinate geometry to two equivalent Si(1) and three equivalent Si(2) atoms. In the fourth Mg site, Mg(4) is bonded in a distorted water-like geometry to one Si(2) and two equivalent Si(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 10-coordinate geometry to two equivalent Mg(1), two equivalent Mg(3), two equivalent Mg(4), three equivalent Mg(2), and one Si(2) atom. In the second Si site, Si(2) is bonded in a 8-coordinate geometry to one Mg(2), one Mg(4), two equivalent Mg(1), three equivalent Mg(3), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Mg2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.492
_cell_length_b   5.165
_cell_length_c   8.455
_cell_angle_alpha   78.576
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   235.076
_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  0.908  0.054  0.713  1.0
  Mg  Mg1  1  0.186  0.495  0.122  1.0
  Mg  Mg2  1  0.686  0.505  0.878  1.0
  Mg  Mg3  1  0.399  0.348  0.508  1.0
  Mg  Mg4  1  0.408  0.946  0.287  1.0
  Mg  Mg5  1  0.386  0.004  0.905  1.0
  Mg  Mg6  1  0.886  0.996  0.095  1.0
  Mg  Mg7  1  0.899  0.652  0.492  1.0
  Si  Si8  1  0.170  0.508  0.792  1.0
  Si  Si9  1  0.951  0.189  0.382  1.0
  Si  Si10  1  0.451  0.811  0.618  1.0
  Si  Si11  1  0.670  0.492  0.208  1.0
[/CIF]
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