data_AgSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   2.92
_cell_length_b   4.3
_cell_length_c   7.11
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   AgSe
_chemical_formula_sum   'Ag2 Se2'
_cell_volume   89.27
_cell_formula_units_Z   2
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
  Ag  Ag0  1  0.0  0.0  0.49  1.0
  Ag  Ag1  1  0.46  0.15  0.63  1.0
  Se  Se2  1  0.0  0.0  0.56  1.0
  Se  Se3  1  0.46  0.15  0.56  1.0

data_AgSe
_symmetry_space_group_name_H-M   P-1
_cell_length_a   2.92
_cell_length_b   4.3
_cell_length_c   7.11
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   AgSe
_chemical_formula_sum   'Ag2 Se2'
_cell_volume   89.27
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-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
  Ag  Ag0  2  0.23  0.08  0.57  1.0
  Se  Se1  2  0.23  0.08  0.5  1.0

Ag Ag Se Se
Ag Ag Se Se 0 2 o o o 1 3 o o o 