data_Mg2Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.71
_cell_length_b   4.71
_cell_length_c   6.12
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   123.52
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2Si
_chemical_formula_sum   'Mg4 Si2'
_cell_volume   113.35
_cell_formula_units_Z   2
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  0.0  0.0  0.0  1.0
  Mg  Mg1  1  0.0  0.0  0.06  1.0
  Mg  Mg2  1  0.23  0.52  0.59  1.0
  Mg  Mg3  1  0.23  0.48  0.53  1.0
  Si  Si4  1  0.23  0.73  0.53  1.0
  Si  Si5  1  0.23  0.27  0.59  1.0

data_Mg2Si
_symmetry_space_group_name_H-M   P1
_cell_length_a   4.46
_cell_length_b   4.71
_cell_length_c   6.12
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   118.24
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2Si
_chemical_formula_sum   'Mg4 Si2'
_cell_volume   113.35
_cell_formula_units_Z   2
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  0.0  0.0  0.0  1.0
  Mg  Mg1  1  0.0  0.0  0.06  1.0
  Mg  Mg2  1  0.48  0.71  0.59  1.0
  Mg  Mg3  1  0.52  0.75  0.53  1.0
  Si  Si4  1  0.27  0.5  0.53  1.0
  Si  Si5  1  0.73  0.96  0.59  1.0

Mg Mg Mg Mg Si Si