data_HfCoHg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.47
_cell_length_b   4.47
_cell_length_c   4.47
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfCoHg
_chemical_formula_sum   'Hf1 Co1 Hg1'
_cell_volume   63.35
_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
  Hf  Hf1  1  0.75  0.75  0.75  1.0
  Co  Co0  1  0.0  0.0  0.0  1.0
  Hg  Hg2  1  0.16  0.16  0.16  1.0

data_HfCoHg
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.47
_cell_length_b   4.47
_cell_length_c   10.96
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   HfCoHg
_chemical_formula_sum   'Hf3 Co3 Hg3'
_cell_volume   190.05
_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
  Hf  Hf0  3  0.0  0.0  0.25  1.0
  Co  Co1  3  0.0  0.0  0.0  1.0
  Hg  Hg2  3  0.0  0.0  0.84  1.0

Hf Co Hg
Hf Co Hg 0 2 o + + 0 2 + o + 0 2 + + o 0 1 o + + 0 1 + o + 0 1 + + o 0 1 + + + 1 2 o o o 
HfCoHg is half-Heusler structured and crystallizes in the trigonal R3m space group. Hf(1) is bonded in a 7-coordinate geometry to four equivalent Co(1) and three equivalent Hg(1) atoms. There are three shorter (2.73 Å) and one longer (2.78 Å) Hf(1)-Co(1) bond length. All Hf(1)-Hg(1) bond lengths are 2.74 Å. Co(1) is bonded in a 5-coordinate geometry to four equivalent Hf(1) and one Hg(1) atom. The Co(1)-Hg(1) bond length is 1.80 Å. Hg(1) is bonded in a 1-coordinate geometry to three equivalent Hf(1) and one Co(1) atom.