data_Mg3Se2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.14
_cell_length_b   9.14
_cell_length_c   9.14
_cell_angle_alpha   24.25
_cell_angle_beta   24.25
_cell_angle_gamma   24.25
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg3Se2
_chemical_formula_sum   'Mg3 Se2'
_cell_volume   113.26
_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  0.0  0.0  0.0  1.0
  Mg  Mg1  1  0.0  0.0  0.94  1.0
  Mg  Mg2  1  0.0  0.0  0.67  1.0
  Se  Se3  1  0.0  0.0  0.48  1.0
  Se  Se4  1  0.0  0.0  0.13  1.0

data_Mg3Se2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.65
_cell_length_b   3.84
_cell_length_c   9.14
_cell_angle_alpha   90.0
_cell_angle_beta   104.04
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Mg3Se2
_chemical_formula_sum   'Mg6 Se4'
_cell_volume   226.52
_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
  Mg  Mg0  2  0.0  0.0  0.0  1.0
  Mg  Mg1  2  0.0  0.0  0.06  1.0
  Mg  Mg2  2  0.0  0.0  0.33  1.0
  Se  Se3  2  0.0  0.0  0.52  1.0
  Se  Se4  2  0.0  0.0  0.87  1.0

Mg Mg Mg Se Se
Mg Mg Mg Se Se 0 1 o o - 0 4 o o o 2 3 o o o 