data_RuSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.08
_cell_length_b   3.79
_cell_length_c   6.02
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   RuSe
_chemical_formula_sum   'Ru2 Se2'
_cell_volume   70.22
_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
  Ru  Ru0  1  0.0  0.0  0.78  1.0
  Ru  Ru1  1  0.54  0.89  0.23  1.0
  Se  Se2  1  0.0  0.0  0.36  1.0
  Se  Se3  1  0.54  0.89  0.66  1.0

data_RuSe
_symmetry_space_group_name_H-M   P-1
_cell_length_a   3.08
_cell_length_b   3.79
_cell_length_c   6.02
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   RuSe
_chemical_formula_sum   'Ru2 Se2'
_cell_volume   70.22
_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
  Ru  Ru0  2  0.27  0.45  0.23  1.0
  Se  Se1  2  0.27  0.45  0.65  1.0

Ru Ru Se Se
Ru Ru Se Se 0 3 - - o 0 3 o - o 1 2 o + o 1 2 + + o 