data_MgSiHg2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.48
_cell_length_b   4.87
_cell_length_c   5.09
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgSiHg2
_chemical_formula_sum   'Mg1 Si1 Hg2'
_cell_volume   86.31
_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
  Mg  Mg2  1  0.0  0.0  0.0  1.0
  Si  Si3  1  0.74  0.0  0.55  1.0
  Hg  Hg0  1  0.74  0.44  0.0  1.0
  Hg  Hg1  1  0.0  0.44  0.55  1.0

data_MgSiHg2
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.48
_cell_length_b   4.87
_cell_length_c   5.09
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgSiHg2
_chemical_formula_sum   'Mg1 Si1 Hg2'
_cell_volume   86.31
_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
  Mg  Mg0  1  0.0  0.0  0.0  1.0
  Si  Si1  1  0.74  0.0  0.55  1.0
  Hg  Hg2  1  0.0  0.44  0.55  1.0
  Hg  Hg3  1  0.74  0.44  0.0  1.0

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