The compound described by Mg7Si crystallizes in the hexagonal P-6m2 space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(3); four Mg(1,1); four Mg(2,2); and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Si(1)Mg12 cuboctahedra; corners with fourteen Mg(1,1)Mg10Si2 cuboctahedra; edges with two equivalent Si(1)Mg12 cuboctahedra; edges with four Mg(1,1)Mg10Si2 cuboctahedra; edges with four equivalent Mg(3)Mg12 cuboctahedra; edges with eight Mg(2,2)Mg10Si2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Si(1)Mg12 cuboctahedra; faces with six Mg(1,1)Mg10Si2 cuboctahedra; and faces with ten Mg(2,2)Mg10Si2 cuboctahedra. In the second Mg site, Mg(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Si(1)Mg12 cuboctahedra; corners with fourteen Mg(1,1)Mg10Si2 cuboctahedra; edges with two equivalent Si(1)Mg12 cuboctahedra; edges with four equivalent Mg(1)Mg10Si2 cuboctahedra; edges with four equivalent Mg(3)Mg12 cuboctahedra; edges with eight equivalent Mg(2)Mg10Si2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Si(1)Mg12 cuboctahedra; faces with six Mg(1,1)Mg10Si2 cuboctahedra; and faces with ten Mg(2,2)Mg10Si2 cuboctahedra. In the third Mg site, Mg(2) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg12 cuboctahedra; corners with fourteen Mg(2,2)Mg10Si2 cuboctahedra; edges with two equivalent Mg(3)Mg12 cuboctahedra; edges with four equivalent Mg(2)Mg10Si2 cuboctahedra; edges with four equivalent Si(1)Mg12 cuboctahedra; edges with eight equivalent Mg(1)Mg10Si2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Si(1)Mg12 cuboctahedra; faces with six Mg(2,2)Mg10Si2 cuboctahedra; and faces with ten Mg(1,1)Mg10Si2 cuboctahedra. In the fourth Mg site, Mg(2) is bonded to two equivalent Mg(3); four Mg(1,1); four Mg(2,2); and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg12 cuboctahedra; corners with fourteen Mg(2,2)Mg10Si2 cuboctahedra; edges with two equivalent Mg(3)Mg12 cuboctahedra; edges with four Mg(2,2)Mg10Si2 cuboctahedra; edges with four equivalent Si(1)Mg12 cuboctahedra; edges with eight Mg(1,1)Mg10Si2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Si(1)Mg12 cuboctahedra; faces with six Mg(2,2)Mg10Si2 cuboctahedra; and faces with ten Mg(1,1)Mg10Si2 cuboctahedra. In the fifth Mg site, Mg(3) is bonded to six Mg(1,1) and six Mg(2,2) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(3)Mg12 cuboctahedra; corners with twelve Mg(2,2)Mg10Si2 cuboctahedra; edges with six Mg(2,2)Mg10Si2 cuboctahedra; edges with twelve Mg(1,1)Mg10Si2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with six Mg(1,1)Mg10Si2 cuboctahedra; faces with six Mg(2,2)Mg10Si2 cuboctahedra; and faces with six equivalent Si(1)Mg12 cuboctahedra. Si(1) is bonded to six Mg(1,1) and six Mg(2,2) atoms to form SiMg12 cuboctahedra that share corners with six equivalent Si(1)Mg12 cuboctahedra; corners with twelve Mg(1,1)Mg10Si2 cuboctahedra; edges with six Mg(1,1)Mg10Si2 cuboctahedra; edges with twelve Mg(2,2)Mg10Si2 cuboctahedra; faces with two equivalent Si(1)Mg12 cuboctahedra; faces with six Mg(1,1)Mg10Si2 cuboctahedra; faces with six Mg(2,2)Mg10Si2 cuboctahedra; and faces with six equivalent Mg(3)Mg12 cuboctahedra. is represented by the CIF card [CIF]
data_Mg7Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.263
_cell_length_b   6.263
_cell_length_c   4.999
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   169.835
_cell_formula_units_Z   1
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  0.834  0.667  0.000  1.0
  Mg  Mg1  1  0.333  0.166  0.000  1.0
  Mg  Mg2  1  0.834  0.166  0.000  1.0
  Mg  Mg3  1  0.497  0.503  0.500  1.0
  Mg  Mg4  1  0.005  0.503  0.500  1.0
  Mg  Mg5  1  0.497  0.995  0.500  1.0
  Mg  Mg6  1  0.000  0.000  0.500  1.0
  Si  Si7  1  0.333  0.667  0.000  1.0
[/CIF]
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The compound described by Mg7Si crystallizes in the hexagonal P-6m2 space group. There are five inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(3); four Mg(1,1); four Mg(2,2); and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Si(1)Mg12 cuboctahedra; corners with fourteen Mg(1,1)Mg10Si2 cuboctahedra; edges with two equivalent Si(1)Mg12 cuboctahedra; edges with four Mg(1,1)Mg10Si2 cuboctahedra; edges with four equivalent Mg(3)Mg12 cuboctahedra; edges with eight Mg(2,2)Mg10Si2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Si(1)Mg12 cuboctahedra; faces with six Mg(1,1)Mg10Si2 cuboctahedra; and faces with ten Mg(2,2)Mg10Si2 cuboctahedra. In the second Mg site, Mg(1) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Si(1)Mg12 cuboctahedra; corners with fourteen Mg(1,1)Mg10Si2 cuboctahedra; edges with two equivalent Si(1)Mg12 cuboctahedra; edges with four equivalent Mg(1)Mg10Si2 cuboctahedra; edges with four equivalent Mg(3)Mg12 cuboctahedra; edges with eight equivalent Mg(2)Mg10Si2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Si(1)Mg12 cuboctahedra; faces with six Mg(1,1)Mg10Si2 cuboctahedra; and faces with ten Mg(2,2)Mg10Si2 cuboctahedra. In the third Mg site, Mg(2) is bonded to two equivalent Mg(3), four equivalent Mg(1), four equivalent Mg(2), and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg12 cuboctahedra; corners with fourteen Mg(2,2)Mg10Si2 cuboctahedra; edges with two equivalent Mg(3)Mg12 cuboctahedra; edges with four equivalent Mg(2)Mg10Si2 cuboctahedra; edges with four equivalent Si(1)Mg12 cuboctahedra; edges with eight equivalent Mg(1)Mg10Si2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Si(1)Mg12 cuboctahedra; faces with six Mg(2,2)Mg10Si2 cuboctahedra; and faces with ten Mg(1,1)Mg10Si2 cuboctahedra. In the fourth Mg site, Mg(2) is bonded to two equivalent Mg(3); four Mg(1,1); four Mg(2,2); and two equivalent Si(1) atoms to form distorted MgMg10Si2 cuboctahedra that share corners with four equivalent Mg(3)Mg12 cuboctahedra; corners with fourteen Mg(2,2)Mg10Si2 cuboctahedra; edges with two equivalent Mg(3)Mg12 cuboctahedra; edges with four Mg(2,2)Mg10Si2 cuboctahedra; edges with four equivalent Si(1)Mg12 cuboctahedra; edges with eight Mg(1,1)Mg10Si2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with two equivalent Si(1)Mg12 cuboctahedra; faces with six Mg(2,2)Mg10Si2 cuboctahedra; and faces with ten Mg(1,1)Mg10Si2 cuboctahedra. In the fifth Mg site, Mg(3) is bonded to six Mg(1,1) and six Mg(2,2) atoms to form MgMg12 cuboctahedra that share corners with six equivalent Mg(3)Mg12 cuboctahedra; corners with twelve Mg(2,2)Mg10Si2 cuboctahedra; edges with six Mg(2,2)Mg10Si2 cuboctahedra; edges with twelve Mg(1,1)Mg10Si2 cuboctahedra; faces with two equivalent Mg(3)Mg12 cuboctahedra; faces with six Mg(1,1)Mg10Si2 cuboctahedra; faces with six Mg(2,2)Mg10Si2 cuboctahedra; and faces with six equivalent Si(1)Mg12 cuboctahedra. Si(1) is bonded to six Mg(1,1) and six Mg(2,2) atoms to form SiMg12 cuboctahedra that share corners with six equivalent Si(1)Mg12 cuboctahedra; corners with twelve Mg(1,1)Mg10Si2 cuboctahedra; edges with six Mg(1,1)Mg10Si2 cuboctahedra; edges with twelve Mg(2,2)Mg10Si2 cuboctahedra; faces with two equivalent Si(1)Mg12 cuboctahedra; faces with six Mg(1,1)Mg10Si2 cuboctahedra; faces with six Mg(2,2)Mg10Si2 cuboctahedra; and faces with six equivalent Mg(3)Mg12 cuboctahedra. is represented by the CIF card [CIF]
data_Mg7Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.263
_cell_length_b   6.263
_cell_length_c   4.999
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   169.835
_cell_formula_units_Z   1
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  0.834  0.667  0.000  1.0
  Mg  Mg1  1  0.333  0.166  0.000  1.0
  Mg  Mg2  1  0.834  0.166  0.000  1.0
  Mg  Mg3  1  0.497  0.503  0.500  1.0
  Mg  Mg4  1  0.005  0.503  0.500  1.0
  Mg  Mg5  1  0.497  0.995  0.500  1.0
  Mg  Mg6  1  0.000  0.000  0.500  1.0
  Si  Si7  1  0.333  0.667  0.000  1.0
[/CIF]
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