data_SrMgSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.64
_cell_length_b   3.64
_cell_length_c   7.31
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   SrMgSe2
_chemical_formula_sum   'Sr1 Mg1 Se2'
_cell_volume   96.84
_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
  Sr  Sr3  1  0.0  0.0  0.66  1.0
  Mg  Mg0  1  0.0  0.0  0.0  1.0
  Se  Se1  1  0.82  0.82  0.68  1.0
  Se  Se2  1  0.82  0.82  0.63  1.0

data_SrMgSe2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.15
_cell_length_b   5.15
_cell_length_c   7.31
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   SrMgSe2
_chemical_formula_sum   'Sr2 Mg2 Se4'
_cell_volume   193.68
_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
  Sr  Sr0  2  0.0  0.0  0.66  1.0
  Mg  Mg1  2  0.0  0.0  0.0  1.0
  Se  Se2  2  0.32  0.5  0.63  1.0
  Se  Se3  2  0.32  0.5  0.68  1.0

Sr Mg Se Se
Sr Mg Se Se 0 3 - - o 0 2 - - o 0 1 o o + 1 3 - - - 1 2 - - - 2 3 o o o 