data_Mg7Bi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.45
_cell_length_b   6.45
_cell_length_c   6.45
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg7Bi
_chemical_formula_sum   'Mg7 Bi1'
_cell_volume   190.14
_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  Mg1  1  0.28  0.0  0.28  1.0
  Mg  Mg2  1  0.0  0.28  0.28  1.0
  Mg  Mg3  1  0.28  0.28  0.56  1.0
  Mg  Mg4  1  0.28  0.56  0.28  1.0
  Mg  Mg5  1  0.56  0.28  0.28  1.0
  Mg  Mg6  1  0.28  0.28  0.0  1.0
  Mg  Mg7  1  0.0  0.0  0.0  1.0
  Bi  Bi0  1  0.56  0.56  0.56  1.0

data_Mg7Bi
_symmetry_space_group_name_H-M   R3m
_cell_length_a   6.45
_cell_length_b   6.45
_cell_length_c   15.81
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Mg7Bi
_chemical_formula_sum   'Mg21 Bi3'
_cell_volume   570.41
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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  9  0.09  0.19  0.62  1.0
  Mg  Mg1  9  0.19  0.09  0.81  1.0
  Mg  Mg2  3  0.0  0.0  0.0  1.0
  Bi  Bi3  3  0.0  0.0  0.44  1.0

Mg Mg Mg Mg Mg Mg Mg Bi
Mg7Bi crystallizes in the trigonal R3m space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 3-coordinate geometry to two equivalent Mg(1), three equivalent Mg(2), and one Bi(1) atom. Both Mg(1)-Mg(1) bond lengths are 1.82 Å. There is one shorter (2.81 Å) and two longer (3.15 Å) Mg(1)-Mg(2) bond lengths. The Mg(1)-Bi(1) bond length is 2.76 Å. In the second Mg site, Mg(2) is bonded in a 7-coordinate geometry to one Mg(3), two equivalent Mg(2), three equivalent Mg(1), and one Bi(1) atom. The Mg(2)-Mg(3) bond length is 2.76 Å. Both Mg(2)-Mg(2) bond lengths are 1.82 Å. The Mg(2)-Bi(1) bond length is 3.15 Å. In the third Mg site, Mg(3) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Mg(2) atoms. Bi(1) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Mg(1) and three equivalent Mg(2) atoms.