data_Co2HgSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.45
_cell_length_b   4.45
_cell_length_c   4.45
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Co2HgSe
_chemical_formula_sum   'Co2 Hg1 Se1'
_cell_volume   62.13
_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
  Co  Co0  1  0.57  0.57  0.57  1.0
  Co  Co1  1  0.72  0.72  0.72  1.0
  Hg  Hg2  1  0.14  0.14  0.14  1.0
  Se  Se3  1  0.0  0.0  0.0  1.0

data_Co2HgSe
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.45
_cell_length_b   4.45
_cell_length_c   10.89
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Co2HgSe
_chemical_formula_sum   'Co6 Hg3 Se3'
_cell_volume   186.38
_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
  Co  Co0  3  0.0  0.0  0.28  1.0
  Co  Co1  3  0.0  0.0  0.43  1.0
  Hg  Hg2  3  0.0  0.0  0.86  1.0
  Se  Se3  3  0.0  0.0  0.0  1.0

Co Co Hg Se
Co Co Hg Se 0 1 o o o 2 3 o o o 
Co2HgSe crystallizes in the trigonal R3m space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a 7-coordinate geometry to one Co(2), three equivalent Hg(1), and three equivalent Se(1) atoms. The Co(1)-Co(2) bond length is 1.56 Å. All Co(1)-Hg(1) bond lengths are 2.77 Å. All Co(1)-Se(1) bond lengths are 2.77 Å. In the second Co site, Co(2) is bonded in a 8-coordinate geometry to one Co(1), three equivalent Hg(1), and four equivalent Se(1) atoms. All Co(2)-Hg(1) bond lengths are 2.77 Å. There are three shorter (2.62 Å) and one longer (3.10 Å) Co(2)-Se(1) bond length. Hg(1) is bonded in a single-bond geometry to three equivalent Co(1), three equivalent Co(2), and one Se(1) atom. The Hg(1)-Se(1) bond length is 1.56 Å. Se(1) is bonded in a single-bond geometry to three equivalent Co(1), four equivalent Co(2), and one Hg(1) atom.