data_Hg2SbSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.2
_cell_length_b   5.2
_cell_length_c   5.2
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Hg2SbSe
_chemical_formula_sum   'Hg2 Sb1 Se1'
_cell_volume   99.69
_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
  Hg  Hg0  1  0.84  0.84  0.84  1.0
  Hg  Hg1  1  0.52  0.52  0.52  1.0
  Sb  Sb2  1  0.68  0.68  0.68  1.0
  Se  Se3  1  0.0  0.0  0.0  1.0

data_Hg2SbSe
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.2
_cell_length_b   5.2
_cell_length_c   12.75
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Hg2SbSe
_chemical_formula_sum   'Hg6 Sb3 Se3'
_cell_volume   299.06
_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
  Hg  Hg0  3  0.0  0.0  0.16  1.0
  Hg  Hg1  3  0.0  0.0  0.48  1.0
  Sb  Sb2  3  0.0  0.0  0.32  1.0
  Se  Se3  3  0.0  0.0  0.0  1.0

Hg Hg Sb Se
Hg Hg Sb Se 0 2 o o o 0 3 + + + 1 2 o o o 
Hg2SbSe crystallizes in the trigonal R3m space group. There are two inequivalent Hg sites. In the first Hg site, Hg(1) is bonded in a distorted linear geometry to one Sb(1) and one Se(1) atom. The Hg(1)-Sb(1) bond length is 2.04 Å. The Hg(1)-Se(1) bond length is 2.04 Å. In the second Hg site, Hg(2) is bonded in a distorted single-bond geometry to one Sb(1) atom. The Hg(2)-Sb(1) bond length is 2.04 Å. Sb(1) is bonded to one Hg(1), one Hg(2), and three equivalent Se(1) atoms to form SbHg2Se3 trigonal bipyramids that share corners with six equivalent Sb(1)Hg2Se3 trigonal bipyramids and  a cornercorner with one Se(1)HgSb3 trigonal pyramid. All Sb(1)-Se(1) bond lengths are 3.01 Å. Se(1) is bonded to one Hg(1) and three equivalent Sb(1) atoms to form distorted SeHgSb3 trigonal pyramids that share  a cornercorner with one Sb(1)Hg2Se3 trigonal bipyramid and corners with six equivalent Se(1)HgSb3 trigonal pyramids.