The compound described by Cs2Se crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded to six equivalent Se(1) atoms to form distorted CsSe6 octahedra that share corners with twelve equivalent Cs(1)Se6 octahedra, corners with twelve equivalent Cs(2)Se5 trigonal bipyramids, edges with six equivalent Cs(1)Se6 octahedra, faces with two equivalent Cs(1)Se6 octahedra, and faces with six equivalent Cs(2)Se5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 51°. In the second Cs site, Cs(2) is bonded to five equivalent Se(1) atoms to form distorted CsSe5 trigonal bipyramids that share corners with twelve equivalent Cs(1)Se6 octahedra, corners with eight equivalent Cs(2)Se5 trigonal bipyramids, edges with six equivalent Cs(2)Se5 trigonal bipyramids, and faces with six equivalent Cs(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 30-60°. Se(1) is bonded in a 11-coordinate geometry to five equivalent Cs(2) and six equivalent Cs(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Cs2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.071
_cell_length_b   6.071
_cell_length_c   8.214
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   262.174
_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
  Cs  Cs0  1  0.000  0.000  0.500  1.0
  Cs  Cs1  1  0.000  0.000  0.000  1.0
  Cs  Cs2  1  0.333  0.667  0.750  1.0
  Cs  Cs3  1  0.667  0.333  0.250  1.0
  Se  Se4  1  0.333  0.667  0.250  1.0
  Se  Se5  1  0.667  0.333  0.750  1.0
[/CIF]
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The compound described by Cs2Se crystallizes in the hexagonal P6_3/mmc space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded to six equivalent Se(1) atoms to form distorted CsSe6 octahedra that share corners with twelve equivalent Cs(1)Se6 octahedra, corners with twelve equivalent Cs(2)Se5 trigonal bipyramids, edges with six equivalent Cs(1)Se6 octahedra, faces with two equivalent Cs(1)Se6 octahedra, and faces with six equivalent Cs(2)Se5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 51°. In the second Cs site, Cs(2) is bonded to five equivalent Se(1) atoms to form distorted CsSe5 trigonal bipyramids that share corners with twelve equivalent Cs(1)Se6 octahedra, corners with eight equivalent Cs(2)Se5 trigonal bipyramids, edges with six equivalent Cs(2)Se5 trigonal bipyramids, and faces with six equivalent Cs(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 30-60°. Se(1) is bonded in a 11-coordinate geometry to five equivalent Cs(2) and six equivalent Cs(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Cs2Se
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.071
_cell_length_b   6.071
_cell_length_c   8.214
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   262.174
_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
  Cs  Cs0  1  0.000  0.000  0.500  1.0
  Cs  Cs1  1  0.000  0.000  0.000  1.0
  Cs  Cs2  1  0.333  0.667  0.750  1.0
  Cs  Cs3  1  0.667  0.333  0.250  1.0
  Se  Se4  1  0.333  0.667  0.250  1.0
  Se  Se5  1  0.667  0.333  0.750  1.0
[/CIF]
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