data_Zn2HgSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.92
_cell_length_b   4.92
_cell_length_c   4.92
_cell_angle_alpha   121.6
_cell_angle_beta   121.6
_cell_angle_gamma   87.25
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Zn2HgSe
_chemical_formula_sum   'Zn2 Hg1 Se1'
_cell_volume   81.86
_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
  Zn  Zn2  1  0.4  0.0  0.78  1.0
  Zn  Zn3  1  0.0  0.4  0.78  1.0
  Hg  Hg0  1  0.0  0.0  0.56  1.0
  Se  Se1  1  0.0  0.0  0.0  1.0

data_Zn2HgSe
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.78
_cell_length_b   6.78
_cell_length_c   4.92
_cell_angle_alpha   90.0
_cell_angle_beta   133.62
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   Zn2HgSe
_chemical_formula_sum   'Zn4 Hg2 Se2'
_cell_volume   163.73
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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
  Zn  Zn0  4  0.3  0.3  0.38  1.0
  Hg  Hg1  2  0.0  0.0  0.56  1.0
  Se  Se2  2  0.0  0.0  0.0  1.0

Zn Zn Hg Se
HgZn2Se crystallizes in the monoclinic Cm space group. Hg(1) is bonded in a distorted see-saw-like geometry to two equivalent Zn(1) and two equivalent Se(1) atoms. Both Hg(1)-Zn(1) bond lengths are 1.67 Å. There is one shorter (2.17 Å) and one longer (2.75 Å) Hg(1)-Se(1) bond length. Zn(1) is bonded in a 2-coordinate geometry to one Hg(1) and two equivalent Se(1) atoms. There is one shorter (2.56 Å) and one longer (2.69 Å) Zn(1)-Se(1) bond length. Se(1) is bonded in a 6-coordinate geometry to two equivalent Hg(1) and four equivalent Zn(1) atoms.