data_KCrSe2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.14
_cell_length_b   5.14
_cell_length_c   5.14
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   KCrSe2
_chemical_formula_sum   'K1 Cr1 Se2'
_cell_volume   95.88
_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
  K  K1  1  0.0  0.0  0.0  1.0
  Cr  Cr0  1  0.82  0.82  0.82  1.0
  Se  Se2  1  0.45  0.45  0.45  1.0
  Se  Se3  1  0.63  0.63  0.63  1.0

data_KCrSe2
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.14
_cell_length_b   5.14
_cell_length_c   12.58
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   KCrSe2
_chemical_formula_sum   'K3 Cr3 Se6'
_cell_volume   287.63
_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
  K  K0  3  0.0  0.0  0.0  1.0
  Cr  Cr1  3  0.0  0.0  0.18  1.0
  Se  Se2  3  0.0  0.0  0.37  1.0
  Se  Se3  3  0.0  0.0  0.55  1.0

K Cr Se Se
K Cr Se Se 0 1 - - - 1 3 o o o 2 3 o o o 
KCrSe2 crystallizes in the trigonal R3m space group. K(1) is bonded in a 7-coordinate geometry to one Cr(1), three equivalent Se(1), and three equivalent Se(2) atoms. The K(1)-Cr(1) bond length is 2.31 Å. All K(1)-Se(1) bond lengths are 3.30 Å. All K(1)-Se(2) bond lengths are 3.00 Å. Cr(1) is bonded in a 5-coordinate geometry to one K(1), one Se(2), and three equivalent Se(1) atoms. The Cr(1)-Se(2) bond length is 2.31 Å. All Cr(1)-Se(1) bond lengths are 3.00 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to three equivalent K(1), three equivalent Cr(1), and one Se(2) atom to form distorted edge-sharing SeK3Cr3Se hexagonal pyramids. The Se(1)-Se(2) bond length is 2.31 Å. In the second Se site, Se(2) is bonded in a 5-coordinate geometry to three equivalent K(1), one Cr(1), and one Se(1) atom.