data_Si2NiHg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.55
_cell_length_b   3.51
_cell_length_c   5.63
_cell_angle_alpha   90.0
_cell_angle_beta   105.54
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Si2NiHg
_chemical_formula_sum   'Si2 Ni1 Hg1'
_cell_volume   67.8
_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
  Si  Si2  1  0.47  0.76  0.0  1.0
  Si  Si3  1  0.65  0.0  0.05  1.0
  Ni  Ni1  1  0.91  0.0  0.11  1.0
  Hg  Hg0  1  0.08  0.76  0.41  1.0

data_Si2NiHg
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.51
_cell_length_b   3.55
_cell_length_c   5.63
_cell_angle_alpha   105.54
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Si2NiHg
_chemical_formula_sum   'Si2 Ni1 Hg1'
_cell_volume   67.8
_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
  Si  Si0  1  0.0  0.35  0.95  1.0
  Si  Si1  1  0.24  0.53  1.0  1.0
  Ni  Ni2  1  0.0  0.09  0.89  1.0
  Hg  Hg3  1  0.24  0.92  0.59  1.0

Si Si Ni Hg
Si Si Ni Hg 0 1 o + o 1 2 o o o 2 3 + - o 