data_HfMg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.51
_cell_length_b   5.51
_cell_length_c   5.51
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfMg
_chemical_formula_sum   'Hf4 Mg4'
_cell_volume   167.21
_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
  Hf  Hf0  1  0.25  0.25  0.25  1.0
  Hf  Hf1  1  0.51  0.26  0.0  1.0
  Hf  Hf2  1  0.26  0.0  0.51  1.0
  Hf  Hf3  1  0.0  0.51  0.26  1.0
  Mg  Mg4  1  0.53  0.53  0.53  1.0
  Mg  Mg5  1  0.22  0.98  0.29  1.0
  Mg  Mg6  1  0.98  0.29  0.22  1.0
  Mg  Mg7  1  0.29  0.22  0.98  1.0

data_HfMg
_symmetry_space_group_name_H-M   R3
_cell_length_a   7.79
_cell_length_b   7.79
_cell_length_c   9.54
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   HfMg
_chemical_formula_sum   'Hf12 Mg12'
_cell_volume   501.63
_cell_formula_units_Z   12
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  'x+1/3, y+2/3, z+2/3'
  5  '-y+1/3, x-y+2/3, z+2/3'
  6  '-x+y+1/3, -x+2/3, z+2/3'
  7  'x+2/3, y+1/3, z+1/3'
  8  '-y+2/3, x-y+1/3, z+1/3'
  9  '-x+y+2/3, -x+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
  Hf  Hf0  9  0.0  0.75  0.26  1.0
  Hf  Hf1  3  0.0  0.0  0.25  1.0
  Mg  Mg2  9  0.06  0.87  0.16  1.0
  Mg  Mg3  3  0.0  0.0  0.53  1.0

Hf Hf Hf Hf Mg Mg Mg Mg
Mg(Hf) crystallizes in the trigonal R3 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 4-coordinate geometry to one Hf(1) and three equivalent Hf(2) atoms. The Mg(1)-Hf(1) bond length is 2.73 Å. All Mg(1)-Hf(2) bond lengths are 2.99 Å. In the second Mg site, Mg(2) is bonded in an L-shaped geometry to one Hf(1) and one Hf(2) atom. The Mg(2)-Hf(1) bond length is 1.53 Å. The Mg(2)-Hf(2) bond length is 1.23 Å. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 3-coordinate geometry to one Mg(1) and three equivalent Mg(2) atoms. In the second Hf site, Hf(2) is bonded in a single-bond geometry to one Mg(1) and one Mg(2) atom.