data_MgHgTe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.15
_cell_length_b   5.15
_cell_length_c   5.15
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   MgHgTe
_chemical_formula_sum   'Mg1 Hg1 Te1'
_cell_volume   96.48
_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  Mg1  1  0.0  0.0  0.0  1.0
  Hg  Hg0  1  0.64  0.64  0.64  1.0
  Te  Te2  1  0.46  0.46  0.46  1.0

data_MgHgTe
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.15
_cell_length_b   5.15
_cell_length_c   12.61
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   MgHgTe
_chemical_formula_sum   'Mg3 Hg3 Te3'
_cell_volume   289.43
_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
  Mg  Mg0  3  0.0  0.0  0.0  1.0
  Hg  Hg1  3  0.0  0.0  0.36  1.0
  Te  Te2  3  0.0  0.0  0.54  1.0

Mg Hg Te
HgMgTe is half-Heusler structured and crystallizes in the trigonal R3m space group. Mg(1) is bonded in a distorted hexagonal planar geometry to three equivalent Hg(1) and three equivalent Te(1) atoms. All Mg(1)-Hg(1) bond lengths are 2.99 Å. All Mg(1)-Te(1) bond lengths are 3.38 Å. Hg(1) is bonded to three equivalent Mg(1) and one Te(1) atom to form HgMg3Te trigonal pyramids that share corners with three equivalent Te(1)Mg3Hg tetrahedra, corners with six equivalent Hg(1)Mg3Te trigonal pyramids, and edges with three equivalent Te(1)Mg3Hg tetrahedra. The Hg(1)-Te(1) bond length is 2.27 Å. Te(1) is bonded to three equivalent Mg(1) and one Hg(1) atom to form distorted TeMg3Hg tetrahedra that share corners with six equivalent Te(1)Mg3Hg tetrahedra, corners with three equivalent Hg(1)Mg3Te trigonal pyramids, and edges with three equivalent Hg(1)Mg3Te trigonal pyramids.