data_MgAg2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.92
_cell_length_b   3.92
_cell_length_c   5.09
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgAg2Se
_chemical_formula_sum   'Mg1 Ag2 Se1'
_cell_volume   78.18
_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  0.0  1.0
  Ag  Ag0  1  0.96  0.0  0.54  1.0
  Ag  Ag1  1  0.0  0.96  0.54  1.0
  Se  Se3  1  0.96  0.96  0.0  1.0

data_MgAg2Se
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.54
_cell_length_b   5.54
_cell_length_c   5.09
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   MgAg2Se
_chemical_formula_sum   'Mg2 Ag4 Se2'
_cell_volume   156.35
_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
  Ag  Ag1  4  0.48  0.48  0.54  1.0
  Se  Se2  2  0.46  0.5  -0.0  1.0

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