data_HfMg2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.05
_cell_length_b   3.05
_cell_length_c   8.47
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfMg2Si
_chemical_formula_sum   'Hf1 Mg2 Si1'
_cell_volume   78.78
_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
  Hf  Hf0  1  0.0  0.0  0.23  1.0
  Mg  Mg1  1  0.53  0.53  0.56  1.0
  Mg  Mg2  1  0.53  0.53  0.91  1.0
  Si  Si3  1  0.0  0.0  0.0  1.0

data_HfMg2Si
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.31
_cell_length_b   4.31
_cell_length_c   8.47
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   HfMg2Si
_chemical_formula_sum   'Hf2 Mg4 Si2'
_cell_volume   157.57
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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  2  0.0  0.0  0.23  1.0
  Mg  Mg1  2  0.03  0.5  0.56  1.0
  Mg  Mg2  2  0.03  0.5  0.91  1.0
  Si  Si3  2  0.0  0.0  0.0  1.0

Hf Mg Mg Si
Hf Mg Mg Si 0 3 o o o 0 1 o o o 0 1 o - o 0 1 - o o 0 1 - - o 1 1 + o o 1 1 o + o 1 2 o o o 2 3 o o + 2 3 o + + 2 3 + o + 2 3 + + + 
Mg2HfSi crystallizes in the monoclinic Cm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 9-coordinate geometry to one Mg(2), four equivalent Mg(1), and four equivalent Hf(1) atoms. The Mg(1)-Mg(2) bond length is 2.92 Å. All Mg(1)-Mg(1) bond lengths are 3.05 Å. There are a spread of Mg(1)-Hf(1) bond distances ranging from 3.45-3.58 Å. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to one Mg(1) and four equivalent Si(1) atoms. There are a spread of Mg(2)-Si(1) bond distances ranging from 2.20-2.40 Å. Hf(1) is bonded in a single-bond geometry to four equivalent Mg(1) and one Si(1) atom. The Hf(1)-Si(1) bond length is 1.97 Å. Si(1) is bonded in a 5-coordinate geometry to four equivalent Mg(2) and one Hf(1) atom.