The material structure described by Cr7Se8 crystallizes in the monoclinic C2/m space group. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent Se(2) and four equivalent Se(3) atoms to form a mixture of edge, corner, and face-sharing CrSe6 octahedra. The corner-sharing octahedral tilt angles range from 49-51°. In the second Cr site, Cr(2) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form a mixture of edge, corner, and face-sharing CrSe6 octahedra. The corner-sharing octahedral tilt angles range from 47-50°. In the third Cr site, Cr(3) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form a mixture of edge, corner, and face-sharing CrSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-51°. In the fourth Cr site, Cr(4) is bonded to one Se(1), one Se(2), and four equivalent Se(3) atoms to form a mixture of edge, corner, and face-sharing CrSe6 octahedra. The corner-sharing octahedral tilt angles range from 47-51°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to one Cr(4), two equivalent Cr(2), and two equivalent Cr(3) atoms to form distorted SeCr5 square pyramids that share corners with three equivalent Se(2)Cr6 pentagonal pyramids, corners with two equivalent Se(1)Cr5 square pyramids, corners with four equivalent Se(3)Cr5 trigonal bipyramids, edges with three equivalent Se(2)Cr6 pentagonal pyramids,  an edgeedge with one Se(1)Cr5 square pyramid, and edges with four equivalent Se(3)Cr5 trigonal bipyramids. In the second Se site, Se(2) is bonded to one Cr(1), one Cr(4), two equivalent Cr(2), and two equivalent Cr(3) atoms to form distorted SeCr6 pentagonal pyramids that share corners with three equivalent Se(2)Cr6 pentagonal pyramids, corners with three equivalent Se(1)Cr5 square pyramids,  an edgeedge with one Se(2)Cr6 pentagonal pyramid, edges with three equivalent Se(1)Cr5 square pyramids, and edges with eight equivalent Se(3)Cr5 trigonal bipyramids. In the third Se site, Se(3) is bonded to one Cr(1), one Cr(2), one Cr(3), and two equivalent Cr(4) atoms to form distorted SeCr5 trigonal bipyramids that share corners with two equivalent Se(1)Cr5 square pyramids, corners with seven equivalent Se(3)Cr5 trigonal bipyramids, edges with four equivalent Se(2)Cr6 pentagonal pyramids, edges with two equivalent Se(1)Cr5 square pyramids, and edges with two equivalent Se(3)Cr5 trigonal bipyramids. is represented by the CIF file [CIF]
data_Cr7Se8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.121
_cell_length_b   7.121
_cell_length_c   8.797
_cell_angle_alpha   54.933
_cell_angle_beta   54.933
_cell_angle_gamma   63.756
_symmetry_Int_Tables_number   1
_cell_volume   294.595
_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
  Cr  Cr0  1  0.500  0.500  0.000  1.0
  Cr  Cr1  1  0.500  0.000  0.500  1.0
  Cr  Cr2  1  0.000  0.500  0.500  1.0
  Cr  Cr3  1  0.231  0.769  0.500  1.0
  Cr  Cr4  1  0.769  0.231  0.500  1.0
  Cr  Cr5  1  0.233  0.233  0.011  1.0
  Cr  Cr6  1  0.767  0.767  0.989  1.0
  Se  Se7  1  0.049  0.049  0.664  1.0
  Se  Se8  1  0.951  0.951  0.336  1.0
  Se  Se9  1  0.536  0.536  0.668  1.0
  Se  Se10  1  0.464  0.464  0.332  1.0
  Se  Se11  1  0.529  0.042  0.169  1.0
  Se  Se12  1  0.958  0.471  0.831  1.0
  Se  Se13  1  0.042  0.529  0.169  1.0
  Se  Se14  1  0.471  0.958  0.831  1.0
[/CIF]
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The material structure described by Cr7Se8 crystallizes in the monoclinic C2/m space group. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent Se(2) and four equivalent Se(3) atoms to form a mixture of edge, corner, and face-sharing CrSe6 octahedra. The corner-sharing octahedral tilt angles range from 49-51°. In the second Cr site, Cr(2) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form a mixture of edge, corner, and face-sharing CrSe6 octahedra. The corner-sharing octahedral tilt angles range from 47-50°. In the third Cr site, Cr(3) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(3) atoms to form a mixture of edge, corner, and face-sharing CrSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-51°. In the fourth Cr site, Cr(4) is bonded to one Se(1), one Se(2), and four equivalent Se(3) atoms to form a mixture of edge, corner, and face-sharing CrSe6 octahedra. The corner-sharing octahedral tilt angles range from 47-51°. There are three inequivalent Se sites. In the first Se site, Se(1) is bonded to one Cr(4), two equivalent Cr(2), and two equivalent Cr(3) atoms to form distorted SeCr5 square pyramids that share corners with three equivalent Se(2)Cr6 pentagonal pyramids, corners with two equivalent Se(1)Cr5 square pyramids, corners with four equivalent Se(3)Cr5 trigonal bipyramids, edges with three equivalent Se(2)Cr6 pentagonal pyramids,  an edgeedge with one Se(1)Cr5 square pyramid, and edges with four equivalent Se(3)Cr5 trigonal bipyramids. In the second Se site, Se(2) is bonded to one Cr(1), one Cr(4), two equivalent Cr(2), and two equivalent Cr(3) atoms to form distorted SeCr6 pentagonal pyramids that share corners with three equivalent Se(2)Cr6 pentagonal pyramids, corners with three equivalent Se(1)Cr5 square pyramids,  an edgeedge with one Se(2)Cr6 pentagonal pyramid, edges with three equivalent Se(1)Cr5 square pyramids, and edges with eight equivalent Se(3)Cr5 trigonal bipyramids. In the third Se site, Se(3) is bonded to one Cr(1), one Cr(2), one Cr(3), and two equivalent Cr(4) atoms to form distorted SeCr5 trigonal bipyramids that share corners with two equivalent Se(1)Cr5 square pyramids, corners with seven equivalent Se(3)Cr5 trigonal bipyramids, edges with four equivalent Se(2)Cr6 pentagonal pyramids, edges with two equivalent Se(1)Cr5 square pyramids, and edges with two equivalent Se(3)Cr5 trigonal bipyramids. is represented by the CIF file [CIF]
data_Cr7Se8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.121
_cell_length_b   7.121
_cell_length_c   8.797
_cell_angle_alpha   54.933
_cell_angle_beta   54.933
_cell_angle_gamma   63.756
_symmetry_Int_Tables_number   1
_cell_volume   294.595
_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
  Cr  Cr0  1  0.500  0.500  0.000  1.0
  Cr  Cr1  1  0.500  0.000  0.500  1.0
  Cr  Cr2  1  0.000  0.500  0.500  1.0
  Cr  Cr3  1  0.231  0.769  0.500  1.0
  Cr  Cr4  1  0.769  0.231  0.500  1.0
  Cr  Cr5  1  0.233  0.233  0.011  1.0
  Cr  Cr6  1  0.767  0.767  0.989  1.0
  Se  Se7  1  0.049  0.049  0.664  1.0
  Se  Se8  1  0.951  0.951  0.336  1.0
  Se  Se9  1  0.536  0.536  0.668  1.0
  Se  Se10  1  0.464  0.464  0.332  1.0
  Se  Se11  1  0.529  0.042  0.169  1.0
  Se  Se12  1  0.958  0.471  0.831  1.0
  Se  Se13  1  0.042  0.529  0.169  1.0
  Se  Se14  1  0.471  0.958  0.831  1.0
[/CIF]
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