data_Mg2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.08
_cell_length_b   9.08
_cell_length_c   9.08
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2Se
_chemical_formula_sum   'Mg16 Se8'
_cell_volume   528.49
_cell_formula_units_Z   8
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  0.6  0.81  0.81  1.0
  Mg  Mg1  1  0.81  0.6  0.81  1.0
  Mg  Mg2  1  0.6  0.6  0.6  1.0
  Mg  Mg3  1  0.81  0.81  0.6  1.0
  Mg  Mg4  1  0.63  0.63  0.45  1.0
  Mg  Mg5  1  0.8  0.63  0.63  1.0
  Mg  Mg6  1  0.63  0.8  0.63  1.0
  Mg  Mg7  1  0.63  0.45  0.63  1.0
  Mg  Mg8  1  0.45  0.63  0.63  1.0
  Mg  Mg9  1  0.63  0.63  0.8  1.0
  Mg  Mg10  1  0.42  0.42  0.59  1.0
  Mg  Mg11  1  0.24  0.42  0.42  1.0
  Mg  Mg12  1  0.42  0.24  0.42  1.0
  Mg  Mg13  1  0.42  0.59  0.42  1.0
  Mg  Mg14  1  0.59  0.42  0.42  1.0
  Mg  Mg15  1  0.42  0.42  0.24  1.0
  Se  Se16  1  0.35  0.35  0.48  1.0
  Se  Se17  1  0.48  0.48  0.48  1.0
  Se  Se18  1  0.35  0.48  0.35  1.0
  Se  Se19  1  0.48  0.35  0.35  1.0
  Se  Se20  1  0.69  0.69  0.56  1.0
  Se  Se21  1  0.56  0.56  0.56  1.0
  Se  Se22  1  0.69  0.56  0.69  1.0
  Se  Se23  1  0.56  0.69  0.69  1.0

data_Mg2Se
_symmetry_space_group_name_H-M   R3m
_cell_length_a   9.08
_cell_length_b   9.08
_cell_length_c   22.23
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Mg2Se
_chemical_formula_sum   'Mg48 Se24'
_cell_volume   1585.48
_cell_formula_units_Z   24
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  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+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
  Mg  Mg0  9  0.06  0.12  0.53  1.0
  Mg  Mg1  9  0.06  0.12  0.32  1.0
  Mg  Mg2  9  0.12  0.06  0.64  1.0
  Mg  Mg3  9  0.12  0.06  0.43  1.0
  Mg  Mg4  9  0.14  0.07  0.26  1.0
  Mg  Mg5  3  0.0  0.0  0.4  1.0
  Se  Se6  9  0.04  0.09  0.6  1.0
  Se  Se7  9  0.09  0.04  0.35  1.0
  Se  Se8  3  0.0  0.0  0.44  1.0
  Se  Se9  3  0.0  0.0  0.52  1.0

Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Se Se Se Se Se Se Se Se
Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Se Se Se Se Se Se Se Se 0 9 o o o 0 6 o o o 0 1 o o o 0 3 o o o 1 9 o o o 1 5 o o o 1 3 o o o 2 21 o o o 2 7 o o o 2 8 o o o 2 23 o o o 2 22 o o o 2 4 o o o 2 20 o o o 3 6 o o o 3 5 o o o 4 21 o o o 5 22 o o o 5 20 o o o 6 23 o o o 6 20 o o o 7 21 o o o 8 21 o o o 9 23 o o o 9 22 o o o 10 17 o o o 11 16 o o o 11 18 o o o 12 16 o o o 12 19 o o o 13 17 o o o 14 17 o o o 15 18 o o o 15 19 o o o 16 19 o o o 16 18 o o o 18 19 o o o 20 22 o o o 20 23 o o o 22 23 o o o 