data_HgAsSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.04
_cell_length_b   4.04
_cell_length_c   6.01
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HgAsSe2
_chemical_formula_sum   'Hg1 As1 Se2'
_cell_volume   98.29
_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  Hg1  1  0.02  0.02  0.04  1.0
  As  As0  1  0.0  0.0  0.06  1.0
  Se  Se2  1  0.0  0.0  0.68  1.0
  Se  Se3  1  0.02  0.02  0.26  1.0

data_HgAsSe2
_symmetry_space_group_name_H-M   Cm
_cell_length_a   5.72
_cell_length_b   5.72
_cell_length_c   6.01
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   HgAsSe2
_chemical_formula_sum   'Hg2 As2 Se4'
_cell_volume   196.58
_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
  Hg  Hg0  2  0.02  0.0  0.04  1.0
  As  As1  2  0.0  0.0  0.06  1.0
  Se  Se2  2  0.0  0.0  0.68  1.0
  Se  Se3  2  0.02  0.0  0.26  1.0

Hg As Se Se
HgAsSe2 is Indium-like structured and crystallizes in the monoclinic Cm space group. The structure is zero-dimensional and consists of two HgAsSe2 clusters. Hg(1) is bonded in a single-bond geometry to one As(1) and one Se(1) atom. The Hg(1)-As(1) bond length is 0.17 Å. The Hg(1)-Se(1) bond length is 2.17 Å. As(1) is bonded in a distorted bent 120 degrees geometry to one Hg(1) and one Se(2) atom. The As(1)-Se(2) bond length is 1.24 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a distorted single-bond geometry to one Hg(1) atom. In the second Se site, Se(2) is bonded in a single-bond geometry to one As(1) atom.