data_[Mg18Hg3]
loop_
 _atom_type_symbol
 _atom_type_electronegativity
 _atom_type_radius
 _atom_type_ionic_radius
[
  Mg  1.3100  1.5000  0.8600
  Hg  2.0000  1.5000  1.2450
]
_symmetry_space_group_name_H-M [R-3m]
_cell_length_a [5.0112]
_cell_length_b [5.0112]
_cell_length_c [21.4337]
_cell_angle_alpha [90.0000]
_cell_angle_beta [90.0000]
_cell_angle_gamma [120.0000]
_symmetry_Int_Tables_number [166]
_chemical_formula_structural [Mg6Hg]
_chemical_formula_sum '[Mg18 Hg3]'
_cell_volume [466.1421]
_cell_formula_units_Z [3]
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  6  0.0000  0.0000  0.1421  1
  Mg  Mg1  6  0.0000  0.0000  0.2876  1
  Mg  Mg2  6  0.0000  0.0000  0.4311  1
  Hg  Hg3  3  0.0000  0.0000  0.0000  1
]