data_Na2Cu
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.18
_cell_length_b   9.18
_cell_length_c   4.88
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   160.52
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2Cu
_chemical_formula_sum   'Na4 Cu2'
_cell_volume   137.32
_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
  Na  Na2  1  0.55  0.49  0.66  1.0
  Na  Na3  1  0.55  0.16  0.66  1.0
  Na  Na4  1  0.55  0.84  0.22  1.0
  Na  Na5  1  0.55  0.51  0.22  1.0
  Cu  Cu0  1  0.55  0.06  0.66  1.0
  Cu  Cu1  1  0.55  0.94  0.22  1.0

data_Na2Cu
_symmetry_space_group_name_H-M   P-1
_cell_length_a   3.11
_cell_length_b   4.88
_cell_length_c   9.18
_cell_angle_alpha   90.0
_cell_angle_beta   99.74
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   Na2Cu
_chemical_formula_sum   'Na4 Cu2'
_cell_volume   137.32
_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
  Na  Na0  2  0.16  0.28  0.16  1.0
  Na  Na1  2  0.49  0.28  0.49  1.0
  Cu  Cu2  2  0.06  0.28  0.06  1.0

Na Na Na Na Cu Cu
Na Na Na Na Cu Cu 0 3 o o o 1 4 o o o 2 5 o o o 