data_KSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.07
_cell_length_b   6.07
_cell_length_c   6.07
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   KSe2
_chemical_formula_sum   'K2 Se4'
_cell_volume   157.89
_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
  K  K0  1  0.0  0.0  0.0  1.0
  K  K1  1  0.14  0.14  0.14  1.0
  Se  Se2  1  0.22  0.22  0.36  1.0
  Se  Se3  1  0.36  0.22  0.22  1.0
  Se  Se4  1  0.22  0.36  0.22  1.0
  Se  Se5  1  0.36  0.36  0.36  1.0

data_KSe2
_symmetry_space_group_name_H-M   R3m
_cell_length_a   6.07
_cell_length_b   6.07
_cell_length_c   14.86
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   KSe2
_chemical_formula_sum   'K6 Se12'
_cell_volume   473.66
_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
  K  K0  3  0.0  0.0  0.0  1.0
  K  K1  3  0.0  0.0  0.86  1.0
  Se  Se2  9  0.05  0.1  0.73  1.0
  Se  Se3  3  0.0  0.0  0.64  1.0

K K Se Se Se Se
KSe2 crystallizes in the trigonal R3m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 4-coordinate geometry to one K(2), three equivalent Se(1), and three equivalent Se(2) atoms. The K(1)-K(2) bond length is 2.15 Å. All K(1)-Se(1) bond lengths are 3.16 Å. All K(1)-Se(2) bond lengths are 3.53 Å. In the second K site, K(2) is bonded in a 4-coordinate geometry to one K(1), three equivalent Se(1), and three equivalent Se(2) atoms. All K(2)-Se(1) bond lengths are 1.86 Å. All K(2)-Se(2) bond lengths are 3.90 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 5-coordinate geometry to one K(1), one K(2), one Se(2), and two equivalent Se(1) atoms. The Se(1)-Se(2) bond length is 1.52 Å. Both Se(1)-Se(1) bond lengths are 0.88 Å. In the second Se site, Se(2) is bonded in a 9-coordinate geometry to three equivalent K(1), three equivalent K(2), and three equivalent Se(1) atoms.