The compound described by FeAs(Se) crystallizes in the monoclinic P2_1/c space group. Fe(1) is bonded to three equivalent As(1) and three equivalent Se(1) atoms to form FeAs3Se3 octahedra that share corners with eight equivalent Fe(1)As3Se3 octahedra, corners with three equivalent As(1)Fe3Se tetrahedra, corners with three equivalent Se(1)Fe3As tetrahedra, and edges with two equivalent Fe(1)As3Se3 octahedra. The corner-sharing octahedral tilt angles range from 53-59°. As(1) is bonded to three equivalent Fe(1) and one Se(1) atom to form distorted AsFe3Se tetrahedra that share corners with three equivalent Fe(1)As3Se3 octahedra, corners with four equivalent As(1)Fe3Se tetrahedra, corners with nine equivalent Se(1)Fe3As tetrahedra, and  an edgeedge with one As(1)Fe3Se tetrahedra. The corner-sharing octahedral tilt angles range from 68-74°. Se(1) is bonded to three equivalent Fe(1) and one As(1) atom to form distorted SeFe3As tetrahedra that share corners with three equivalent Fe(1)As3Se3 octahedra, corners with four equivalent Se(1)Fe3As tetrahedra, corners with nine equivalent As(1)Fe3Se tetrahedra, and  an edgeedge with one Se(1)Fe3As tetrahedra. The corner-sharing octahedral tilt angles range from 76-79°. is represented by the CIF card [CIF]
data_FeAsSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.836
_cell_length_b   5.893
_cell_length_c   5.935
_cell_angle_alpha   112.867
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   188.059
_cell_formula_units_Z   4
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
  Fe  Fe0  1  0.500  0.724  0.209  1.0
  Fe  Fe1  1  0.000  0.276  0.291  1.0
  Fe  Fe2  1  0.500  0.276  0.791  1.0
  Fe  Fe3  1  1.000  0.724  0.709  1.0
  As  As4  1  0.137  0.857  0.122  1.0
  As  As5  1  0.637  0.143  0.378  1.0
  As  As6  1  0.863  0.143  0.878  1.0
  As  As7  1  0.363  0.857  0.622  1.0
  Se  Se8  1  0.869  0.656  0.321  1.0
  Se  Se9  1  0.369  0.344  0.179  1.0
  Se  Se10  1  0.131  0.344  0.679  1.0
  Se  Se11  1  0.631  0.656  0.821  1.0
[/CIF]
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The compound described by FeAs(Se) crystallizes in the monoclinic P2_1/c space group. Fe(1) is bonded to three equivalent As(1) and three equivalent Se(1) atoms to form FeAs3Se3 octahedra that share corners with eight equivalent Fe(1)As3Se3 octahedra, corners with three equivalent As(1)Fe3Se tetrahedra, corners with three equivalent Se(1)Fe3As tetrahedra, and edges with two equivalent Fe(1)As3Se3 octahedra. The corner-sharing octahedral tilt angles range from 53-59°. As(1) is bonded to three equivalent Fe(1) and one Se(1) atom to form distorted AsFe3Se tetrahedra that share corners with three equivalent Fe(1)As3Se3 octahedra, corners with four equivalent As(1)Fe3Se tetrahedra, corners with nine equivalent Se(1)Fe3As tetrahedra, and  an edgeedge with one As(1)Fe3Se tetrahedra. The corner-sharing octahedral tilt angles range from 68-74°. Se(1) is bonded to three equivalent Fe(1) and one As(1) atom to form distorted SeFe3As tetrahedra that share corners with three equivalent Fe(1)As3Se3 octahedra, corners with four equivalent Se(1)Fe3As tetrahedra, corners with nine equivalent As(1)Fe3Se tetrahedra, and  an edgeedge with one Se(1)Fe3As tetrahedra. The corner-sharing octahedral tilt angles range from 76-79°. is represented by the CIF card [CIF]
data_FeAsSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.836
_cell_length_b   5.893
_cell_length_c   5.935
_cell_angle_alpha   112.867
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   188.059
_cell_formula_units_Z   4
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
  Fe  Fe0  1  0.500  0.724  0.209  1.0
  Fe  Fe1  1  0.000  0.276  0.291  1.0
  Fe  Fe2  1  0.500  0.276  0.791  1.0
  Fe  Fe3  1  1.000  0.724  0.709  1.0
  As  As4  1  0.137  0.857  0.122  1.0
  As  As5  1  0.637  0.143  0.378  1.0
  As  As6  1  0.863  0.143  0.878  1.0
  As  As7  1  0.363  0.857  0.622  1.0
  Se  Se8  1  0.869  0.656  0.321  1.0
  Se  Se9  1  0.369  0.344  0.179  1.0
  Se  Se10  1  0.131  0.344  0.679  1.0
  Se  Se11  1  0.631  0.656  0.821  1.0
[/CIF]
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