data_Mg2Be2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.66
_cell_length_b   7.66
_cell_length_c   7.66
_cell_angle_alpha   154.91
_cell_angle_beta   154.91
_cell_angle_gamma   35.77
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Mg2Be2Se
_chemical_formula_sum   'Mg2 Be2 Se1'
_cell_volume   80.78
_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
  Mg  Mg2  1  0.0  0.0  0.81  1.0
  Mg  Mg3  1  0.0  0.0  0.77  1.0
  Be  Be0  1  0.0  0.66  0.65  1.0
  Be  Be1  1  0.66  0.0  0.65  1.0
  Se  Se4  1  0.0  0.0  0.0  1.0

data_Mg2Be2Se
_symmetry_space_group_name_H-M   Cm
_cell_length_a   4.71
_cell_length_b   4.71
_cell_length_c   7.66
_cell_angle_alpha   90.0
_cell_angle_beta   107.89
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Mg2Be2Se
_chemical_formula_sum   'Mg4 Be4 Se2'
_cell_volume   161.55
_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  0.19  1.0
  Mg  Mg1  2  0.0  0.0  0.23  1.0
  Be  Be2  4  0.33  0.33  0.02  1.0
  Se  Se3  2  0.0  0.0  0.0  1.0

Mg Mg Be Be Se
Mg Mg Be Be Se 0 1 o o o 2 4 o + + 3 4 + o + 