data_HfSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.86
_cell_length_b   4.86
_cell_length_c   4.86
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   HfSe
_chemical_formula_sum   'Hf2 Se2'
_cell_volume   81.26
_cell_formula_units_Z   2
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
  Hf  Hf0  1  0.44  0.44  0.44  1.0
  Hf  Hf1  1  0.16  0.16  0.16  1.0
  Se  Se2  1  0.0  0.0  0.0  1.0
  Se  Se3  1  0.72  0.72  0.72  1.0

data_HfSe
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.86
_cell_length_b   4.86
_cell_length_c   11.91
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   HfSe
_chemical_formula_sum   'Hf6 Se6'
_cell_volume   243.79
_cell_formula_units_Z   6
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
  Hf  Hf0  3  0.0  0.0  0.56  1.0
  Hf  Hf1  3  0.0  0.0  0.84  1.0
  Se  Se2  3  0.0  0.0  0.0  1.0
  Se  Se3  3  0.0  0.0  0.28  1.0

Hf Hf Se Se
Hf Hf Se Se 0 1 o o o 0 1 o o + 0 1 o + o 0 1 + o o 0 2 o o + 0 2 o + o 0 2 + o o 0 3 - o o 0 3 o - o 0 3 o o - 0 3 o o o 1 2 o o o 1 3 o - - 1 3 - o - 1 3 - - o 2 3 o - - 2 3 - o - 2 3 - - o 2 3 - - - 
HfSe is Zintl Phase structured and crystallizes in the trigonal R3m space group. There are two inequivalent Hf sites. In the first Hf site, Hf(1) is bonded in a 11-coordinate geometry to four equivalent Hf(2), three equivalent Se(1), and four equivalent Se(2) atoms. There are three shorter (2.88 Å) and one longer (3.35 Å) Hf(1)-Hf(2) bond length. All Hf(1)-Se(1) bond lengths are 3.07 Å. There are three shorter (2.88 Å) and one longer (3.35 Å) Hf(1)-Se(2) bond length. In the second Hf site, Hf(2) is bonded in a single-bond geometry to four equivalent Hf(1), one Se(1), and three equivalent Se(2) atoms. The Hf(2)-Se(1) bond length is 1.87 Å. All Hf(2)-Se(2) bond lengths are 3.07 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a single-bond geometry to one Hf(2), three equivalent Hf(1), and three equivalent Se(2) atoms. All Se(1)-Se(2) bond lengths are 2.88 Å. In the second Se site, Se(2) is bonded in a 10-coordinate geometry to three equivalent Hf(2), four equivalent Hf(1), and three equivalent Se(1) atoms.