data_Ca3HgF
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.99
_cell_length_b   4.99
_cell_length_c   4.99
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca3HgF
_chemical_formula_sum   'Ca3 Hg1 F1'
_cell_volume   123.99
_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
  Ca  Ca0  1  0.0  0.49  0.0  1.0
  Ca  Ca1  1  0.0  0.0  0.49  1.0
  Ca  Ca2  1  0.49  0.0  0.0  1.0
  Hg  Hg3  1  0.49  0.49  0.49  1.0
  F  F4  1  0.0  0.0  0.0  1.0

data_Ca3HgF
_symmetry_space_group_name_H-M   R3m
_cell_length_a   7.05
_cell_length_b   7.05
_cell_length_c   8.64
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Ca3HgF
_chemical_formula_sum   'Ca9 Hg3 F3'
_cell_volume   371.96
_cell_formula_units_Z   3
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+1/3, z+1/3'
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
  Ca  Ca0  9  0.17  0.34  0.83  1.0
  Hg  Hg1  3  0.0  0.0  0.49  1.0
  F  F2  3  0.0  0.0  0.0  1.0

Ca Ca Ca Hg F
Ca3HgF is (Cubic) Perovskite structured and crystallizes in the trigonal R3m space group. Ca(1) is bonded in a linear geometry to four equivalent Hg(1) and two equivalent F(1) atoms. There are a spread of Ca(1)-Hg(1) bond distances ranging from 3.48-3.57 Å. There is one shorter (2.46 Å) and one longer (2.53 Å) Ca(1)-F(1) bond length. Hg(1) is bonded to twelve equivalent Ca(1) atoms to form HgCa12 cuboctahedra that share corners with twelve equivalent Hg(1)Ca12 cuboctahedra, faces with six equivalent Hg(1)Ca12 cuboctahedra, and faces with eight equivalent F(1)Ca6 octahedra. F(1) is bonded to six equivalent Ca(1) atoms to form FCa6 octahedra that share corners with six equivalent F(1)Ca6 octahedra and faces with eight equivalent Hg(1)Ca12 cuboctahedra. The corner-sharing octahedra are not tilted.