data_CuHg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.15
_cell_length_b   4.68
_cell_length_c   4.69
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   CuHg
_chemical_formula_sum   'Cu2 Hg2'
_cell_volume   69.13
_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
  Cu  Cu0  1  0.0  0.0  0.71  1.0
  Cu  Cu1  1  0.57  0.34  0.98  1.0
  Hg  Hg2  1  0.0  0.34  0.16  1.0
  Hg  Hg3  1  0.57  0.0  0.53  1.0

data_CuHg
_symmetry_space_group_name_H-M   P-1
_cell_length_a   3.15
_cell_length_b   4.68
_cell_length_c   4.69
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   2
_chemical_formula_structural   CuHg
_chemical_formula_sum   'Cu2 Hg2'
_cell_volume   69.13
_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
  Cu  Cu0  2  0.29  0.17  0.63  1.0
  Hg  Hg1  2  0.29  0.83  0.18  1.0

Cu Cu Hg Hg
Cu Cu Hg Hg 0 3 - o o 1 2 + o + 