The compound described by CsAs2Se3 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 11-coordinate geometry to two equivalent As(1), two equivalent Se(2), three equivalent Se(4), and four equivalent Se(3) atoms. In the second Cs site, Cs(2) is bonded in a 11-coordinate geometry to two equivalent As(1), two equivalent Se(3), three equivalent Se(1), and four equivalent Se(2) atoms. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 2-coordinate geometry to one Cs(1), one Cs(2), one Se(2), and one Se(3) atom. In the second As site, As(2) is bonded in a 3-coordinate geometry to one Se(4) and two equivalent Se(3) atoms. In the third As site, As(3) is bonded in a distorted trigonal non-coplanar geometry to one Se(1) and two equivalent Se(2) atoms. There are four inequivalent Se sites. In the first Se site, Se(4) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Cs(1) and one As(2) atom. In the second Se site, Se(1) is bonded in a 1-coordinate geometry to three equivalent Cs(2) and one As(3) atom. In the third Se site, Se(2) is bonded in a 2-coordinate geometry to one Cs(1), two equivalent Cs(2), one As(1), and one As(3) atom. In the fourth Se site, Se(3) is bonded to one Cs(2), two equivalent Cs(1), one As(1), and one As(2) atom to form a mixture of distorted corner and edge-sharing SeCs3As2 square pyramids. is represented by the CIF card [CIF]
data_CsAs2Se3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.554
_cell_length_b   13.610
_cell_length_c   15.048
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1547.159
_cell_formula_units_Z   8
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  0.250  0.915  0.092  1.0
  Cs  Cs1  1  0.250  0.585  0.592  1.0
  Cs  Cs2  1  0.750  0.085  0.908  1.0
  Cs  Cs3  1  0.250  0.594  0.922  1.0
  Cs  Cs4  1  0.250  0.906  0.422  1.0
  Cs  Cs5  1  0.750  0.094  0.578  1.0
  Cs  Cs6  1  0.750  0.406  0.078  1.0
  Cs  Cs7  1  0.750  0.415  0.408  1.0
  As  As8  1  0.418  0.230  0.743  1.0
  As  As9  1  0.750  0.725  0.484  1.0
  As  As10  1  0.250  0.565  0.213  1.0
  As  As11  1  0.750  0.775  0.984  1.0
  As  As12  1  0.918  0.730  0.757  1.0
  As  As13  1  0.582  0.770  0.257  1.0
  As  As14  1  0.418  0.270  0.243  1.0
  As  As15  1  0.250  0.275  0.516  1.0
  As  As16  1  0.582  0.730  0.757  1.0
  As  As17  1  0.082  0.270  0.243  1.0
  As  As18  1  0.250  0.935  0.713  1.0
  As  As19  1  0.250  0.225  0.016  1.0
  As  As20  1  0.750  0.435  0.787  1.0
  As  As21  1  0.918  0.770  0.257  1.0
  As  As22  1  0.750  0.065  0.287  1.0
  As  As23  1  0.082  0.230  0.743  1.0
  Se  Se24  1  0.250  0.433  0.112  1.0
  Se  Se25  1  0.993  0.644  0.145  1.0
  Se  Se26  1  0.014  0.167  0.114  1.0
  Se  Se27  1  0.486  0.333  0.614  1.0
  Se  Se28  1  0.514  0.833  0.886  1.0
  Se  Se29  1  0.493  0.356  0.855  1.0
  Se  Se30  1  0.514  0.667  0.386  1.0
  Se  Se31  1  0.507  0.856  0.645  1.0
  Se  Se32  1  0.250  0.101  0.908  1.0
  Se  Se33  1  0.007  0.144  0.355  1.0
  Se  Se34  1  0.750  0.933  0.388  1.0
  Se  Se35  1  0.014  0.333  0.614  1.0
  Se  Se36  1  0.250  0.067  0.612  1.0
  Se  Se37  1  0.007  0.356  0.855  1.0
  Se  Se38  1  0.993  0.856  0.645  1.0
  Se  Se39  1  0.750  0.601  0.592  1.0
  Se  Se40  1  0.250  0.399  0.408  1.0
  Se  Se41  1  0.750  0.899  0.092  1.0
  Se  Se42  1  0.486  0.167  0.114  1.0
  Se  Se43  1  0.986  0.667  0.386  1.0
  Se  Se44  1  0.507  0.644  0.145  1.0
  Se  Se45  1  0.750  0.567  0.888  1.0
  Se  Se46  1  0.493  0.144  0.355  1.0
  Se  Se47  1  0.986  0.833  0.886  1.0
[/CIF]
.
The compound described by CsAs2Se3 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 11-coordinate geometry to two equivalent As(1), two equivalent Se(2), three equivalent Se(4), and four equivalent Se(3) atoms. In the second Cs site, Cs(2) is bonded in a 11-coordinate geometry to two equivalent As(1), two equivalent Se(3), three equivalent Se(1), and four equivalent Se(2) atoms. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 2-coordinate geometry to one Cs(1), one Cs(2), one Se(2), and one Se(3) atom. In the second As site, As(2) is bonded in a 3-coordinate geometry to one Se(4) and two equivalent Se(3) atoms. In the third As site, As(3) is bonded in a distorted trigonal non-coplanar geometry to one Se(1) and two equivalent Se(2) atoms. There are four inequivalent Se sites. In the first Se site, Se(4) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Cs(1) and one As(2) atom. In the second Se site, Se(1) is bonded in a 1-coordinate geometry to three equivalent Cs(2) and one As(3) atom. In the third Se site, Se(2) is bonded in a 2-coordinate geometry to one Cs(1), two equivalent Cs(2), one As(1), and one As(3) atom. In the fourth Se site, Se(3) is bonded to one Cs(2), two equivalent Cs(1), one As(1), and one As(2) atom to form a mixture of distorted corner and edge-sharing SeCs3As2 square pyramids. is represented by the CIF card [CIF]
data_CsAs2Se3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.554
_cell_length_b   13.610
_cell_length_c   15.048
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   1547.159
_cell_formula_units_Z   8
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  0.250  0.915  0.092  1.0
  Cs  Cs1  1  0.250  0.585  0.592  1.0
  Cs  Cs2  1  0.750  0.085  0.908  1.0
  Cs  Cs3  1  0.250  0.594  0.922  1.0
  Cs  Cs4  1  0.250  0.906  0.422  1.0
  Cs  Cs5  1  0.750  0.094  0.578  1.0
  Cs  Cs6  1  0.750  0.406  0.078  1.0
  Cs  Cs7  1  0.750  0.415  0.408  1.0
  As  As8  1  0.418  0.230  0.743  1.0
  As  As9  1  0.750  0.725  0.484  1.0
  As  As10  1  0.250  0.565  0.213  1.0
  As  As11  1  0.750  0.775  0.984  1.0
  As  As12  1  0.918  0.730  0.757  1.0
  As  As13  1  0.582  0.770  0.257  1.0
  As  As14  1  0.418  0.270  0.243  1.0
  As  As15  1  0.250  0.275  0.516  1.0
  As  As16  1  0.582  0.730  0.757  1.0
  As  As17  1  0.082  0.270  0.243  1.0
  As  As18  1  0.250  0.935  0.713  1.0
  As  As19  1  0.250  0.225  0.016  1.0
  As  As20  1  0.750  0.435  0.787  1.0
  As  As21  1  0.918  0.770  0.257  1.0
  As  As22  1  0.750  0.065  0.287  1.0
  As  As23  1  0.082  0.230  0.743  1.0
  Se  Se24  1  0.250  0.433  0.112  1.0
  Se  Se25  1  0.993  0.644  0.145  1.0
  Se  Se26  1  0.014  0.167  0.114  1.0
  Se  Se27  1  0.486  0.333  0.614  1.0
  Se  Se28  1  0.514  0.833  0.886  1.0
  Se  Se29  1  0.493  0.356  0.855  1.0
  Se  Se30  1  0.514  0.667  0.386  1.0
  Se  Se31  1  0.507  0.856  0.645  1.0
  Se  Se32  1  0.250  0.101  0.908  1.0
  Se  Se33  1  0.007  0.144  0.355  1.0
  Se  Se34  1  0.750  0.933  0.388  1.0
  Se  Se35  1  0.014  0.333  0.614  1.0
  Se  Se36  1  0.250  0.067  0.612  1.0
  Se  Se37  1  0.007  0.356  0.855  1.0
  Se  Se38  1  0.993  0.856  0.645  1.0
  Se  Se39  1  0.750  0.601  0.592  1.0
  Se  Se40  1  0.250  0.399  0.408  1.0
  Se  Se41  1  0.750  0.899  0.092  1.0
  Se  Se42  1  0.486  0.167  0.114  1.0
  Se  Se43  1  0.986  0.667  0.386  1.0
  Se  Se44  1  0.507  0.644  0.145  1.0
  Se  Se45  1  0.750  0.567  0.888  1.0
  Se  Se46  1  0.493  0.144  0.355  1.0
  Se  Se47  1  0.986  0.833  0.886  1.0
[/CIF]
.