data_Mg2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.68
_cell_length_b   7.68
_cell_length_c   3.91
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2Se
_chemical_formula_sum   'Mg6 Se3'
_cell_volume   199.76
_cell_formula_units_Z   3
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  0.06  0.0  0.95  1.0
  Mg  Mg1  1  0.97  0.78  0.95  1.0
  Mg  Mg2  1  0.81  0.87  0.95  1.0
  Mg  Mg3  1  0.56  0.0  0.0  1.0
  Mg  Mg4  1  0.72  0.95  0.0  1.0
  Mg  Mg5  1  0.56  0.71  0.0  1.0
  Se  Se6  1  0.0  0.43  0.95  1.0
  Se  Se7  1  0.84  0.22  0.95  1.0
  Se  Se8  1  0.0  0.0  0.0  1.0

data_Mg2Se
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.91
_cell_length_b   7.68
_cell_length_c   7.68
_cell_angle_alpha   120.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2Se
_chemical_formula_sum   'Mg6 Se3'
_cell_volume   199.76
_cell_formula_units_Z   3
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  0.72  0.95  1.0
  Mg  Mg1  1  -0.0  0.56  0.71  1.0
  Mg  Mg2  1  -0.0  0.56  0.0  1.0
  Mg  Mg3  1  0.95  0.06  0.0  1.0
  Mg  Mg4  1  0.95  0.81  0.87  1.0
  Mg  Mg5  1  0.95  0.97  0.78  1.0
  Se  Se6  1  0.0  0.0  0.0  1.0
  Se  Se7  1  0.95  0.0  0.43  1.0
  Se  Se8  1  0.95  0.84  0.22  1.0

Mg Mg Mg Mg Mg Mg Se Se Se
Mg Mg Mg Mg Mg Mg Se Se Se 0 8 o o + 0 1 - - o 1 8 + + + 1 2 o o o 2 4 o o + 2 8 + + + 2 5 o o + 3 4 o - o 4 5 o o o 4 7 o + - 6 7 - o o 