data_Nb2Cu
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.08
_cell_length_b   5.08
_cell_length_c   5.08
_cell_angle_alpha   103.27
_cell_angle_beta   103.27
_cell_angle_gamma   122.74
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Nb2Cu
_chemical_formula_sum   'Nb4 Cu2'
_cell_volume   96.87
_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
  Nb  Nb2  1  0.98  0.13  0.0  1.0
  Nb  Nb3  1  0.18  0.02  0.43  1.0
  Nb  Nb4  1  0.98  0.18  0.43  1.0
  Nb  Nb5  1  0.18  0.98  0.0  1.0
  Cu  Cu0  1  0.0  0.0  0.22  1.0
  Cu  Cu1  1  0.0  0.0  0.65  1.0

data_Nb2Cu
_symmetry_space_group_name_H-M   P1
_cell_length_a   4.87
_cell_length_b   5.08
_cell_length_c   5.08
_cell_angle_alpha   76.73
_cell_angle_beta   61.37
_cell_angle_gamma   61.37
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Nb2Cu
_chemical_formula_sum   'Nb4 Cu2'
_cell_volume   96.87
_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
  Nb  Nb0  1  0.02  0.15  0.57  1.0
  Nb  Nb1  1  0.13  0.85  -0.0  1.0
  Nb  Nb2  1  0.18  0.8  0.57  1.0
  Nb  Nb3  1  0.98  0.2  -0.0  1.0
  Cu  Cu4  1  0.0  0.0  0.35  1.0
  Cu  Cu5  1  0.0  0.0  0.78  1.0

Nb Nb Nb Nb Cu Cu
Nb Nb Nb Nb Cu Cu 0 3 + - o 0 4 + o o 0 5 + o - 1 4 o o o 1 2 - o o 1 5 o o o 2 4 + o o 2 5 + o o 3 5 o + - 3 4 o + o 