data_Cu2Se3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.87
_cell_length_b   3.87
_cell_length_c   7.01
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Cu2Se3
_chemical_formula_sum   'Cu2 Se3'
_cell_volume   90.7
_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
  Cu  Cu0  1  0.93  0.12  0.37  1.0
  Cu  Cu1  1  0.0  0.23  0.63  1.0
  Se  Se2  1  0.0  0.0  0.0  1.0
  Se  Se3  1  0.93  0.12  0.58  1.0
  Se  Se4  1  0.0  0.23  0.42  1.0

data_Cu2Se3
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.87
_cell_length_b   3.87
_cell_length_c   7.01
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Cu2Se3
_chemical_formula_sum   'Cu2 Se3'
_cell_volume   90.7
_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
  Cu  Cu0  1  0.0  0.23  0.63  1.0
  Cu  Cu1  1  0.93  0.12  0.37  1.0
  Se  Se2  1  0.0  0.0  0.0  1.0
  Se  Se3  1  0.0  0.23  0.42  1.0
  Se  Se4  1  0.93  0.12  0.58  1.0

Cu Cu Se Se Se
Cu Cu Se Se Se 0 4 + o o 0 2 + o o 1 3 - o o 1 2 o o + 2 3 - o - 2 4 o o o 