data_Cu2As
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.42
_cell_length_b   4.42
_cell_length_c   4.42
_cell_angle_alpha   136.91
_cell_angle_beta   133.51
_cell_angle_gamma   65.24
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Cu2As
_chemical_formula_sum   'Cu2 As1'
_cell_volume   42.07
_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  Cu1  1  0.0  0.0  0.97  1.0
  Cu  Cu2  1  0.0  0.0  0.47  1.0
  As  As0  1  0.0  0.0  0.0  1.0

data_Cu2As
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.24
_cell_length_b   3.49
_cell_length_c   4.42
_cell_angle_alpha   113.24
_cell_angle_beta   111.55
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Cu2As
_chemical_formula_sum   'Cu2 As1'
_cell_volume   42.07
_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  0.47  0.47  1.0
  Cu  Cu1  1  0.0  0.97  0.97  1.0
  As  As2  1  0.0  0.0  0.0  1.0

Cu Cu As
Cu Cu As 0 2 o o + 0 1 o o + 0 1 o o o 1 2 o o o 1 2 o o + 