The material described by MnBi2Se4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent Se(4) and four equivalent Se(3) atoms to form MnSe6 octahedra that share corners with four equivalent Bi(1)Se6 octahedra, edges with two equivalent Mn(1)Se6 octahedra, and edges with six equivalent Bi(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 7°. In the second Mn site, Mn(2) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form MnSe6 octahedra that share corners with two equivalent Bi(1)Se6 octahedra, corners with four equivalent Bi(2)Se5 square pyramids, edges with two equivalent Mn(2)Se6 octahedra, and edges with six equivalent Bi(2)Se5 square pyramids. The corner-sharing octahedral tilt angles are 50°. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one Se(2), two equivalent Se(4), and three equivalent Se(3) atoms to form BiSe6 octahedra that share  a cornercorner with one Mn(2)Se6 octahedra, corners with two equivalent Mn(1)Se6 octahedra, corners with two equivalent Bi(2)Se5 square pyramids, edges with three equivalent Mn(1)Se6 octahedra, and edges with four equivalent Bi(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-50°. In the second Bi site, Bi(2) is bonded to two equivalent Se(2) and three equivalent Se(1) atoms to form BiSe5 square pyramids that share corners with two equivalent Mn(2)Se6 octahedra, corners with two equivalent Bi(1)Se6 octahedra, edges with three equivalent Mn(2)Se6 octahedra, and edges with four equivalent Bi(2)Se5 square pyramids. The corner-sharing octahedral tilt angles range from 12-62°. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Mn(2) and three equivalent Bi(2) atoms to form a mixture of corner and edge-sharing SeMn2Bi3 square pyramids. In the second Se site, Se(2) is bonded in a distorted rectangular see-saw-like geometry to one Mn(2), one Bi(1), and two equivalent Bi(2) atoms. In the third Se site, Se(3) is bonded to two equivalent Mn(1) and three equivalent Bi(1) atoms to form a mixture of corner and edge-sharing SeMn2Bi3 square pyramids. In the fourth Se site, Se(4) is bonded in a distorted T-shaped geometry to one Mn(1) and two equivalent Bi(1) atoms. is represented by the CIF card [CIF]
data_Mn(BiSe2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.079
_cell_length_b   6.968
_cell_length_c   14.116
_cell_angle_alpha   87.490
_cell_angle_beta   81.693
_cell_angle_gamma   72.981
_symmetry_Int_Tables_number   1
_cell_volume   379.589
_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
  Mn  Mn0  1  0.000  0.500  0.500  1.0
  Mn  Mn1  1  0.000  0.000  0.000  1.0
  Bi  Bi2  1  0.221  0.930  0.628  1.0
  Bi  Bi3  1  0.779  0.070  0.372  1.0
  Bi  Bi4  1  0.352  0.433  0.863  1.0
  Bi  Bi5  1  0.648  0.567  0.137  1.0
  Se  Se6  1  0.657  0.730  0.956  1.0
  Se  Se7  1  0.343  0.270  0.044  1.0
  Se  Se8  1  0.013  0.148  0.826  1.0
  Se  Se9  1  0.987  0.852  0.174  1.0
  Se  Se10  1  0.601  0.245  0.554  1.0
  Se  Se11  1  0.399  0.755  0.446  1.0
  Se  Se12  1  0.834  0.655  0.678  1.0
  Se  Se13  1  0.166  0.345  0.322  1.0
[/CIF]
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The material described by MnBi2Se4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent Se(4) and four equivalent Se(3) atoms to form MnSe6 octahedra that share corners with four equivalent Bi(1)Se6 octahedra, edges with two equivalent Mn(1)Se6 octahedra, and edges with six equivalent Bi(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 7°. In the second Mn site, Mn(2) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form MnSe6 octahedra that share corners with two equivalent Bi(1)Se6 octahedra, corners with four equivalent Bi(2)Se5 square pyramids, edges with two equivalent Mn(2)Se6 octahedra, and edges with six equivalent Bi(2)Se5 square pyramids. The corner-sharing octahedral tilt angles are 50°. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one Se(2), two equivalent Se(4), and three equivalent Se(3) atoms to form BiSe6 octahedra that share  a cornercorner with one Mn(2)Se6 octahedra, corners with two equivalent Mn(1)Se6 octahedra, corners with two equivalent Bi(2)Se5 square pyramids, edges with three equivalent Mn(1)Se6 octahedra, and edges with four equivalent Bi(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-50°. In the second Bi site, Bi(2) is bonded to two equivalent Se(2) and three equivalent Se(1) atoms to form BiSe5 square pyramids that share corners with two equivalent Mn(2)Se6 octahedra, corners with two equivalent Bi(1)Se6 octahedra, edges with three equivalent Mn(2)Se6 octahedra, and edges with four equivalent Bi(2)Se5 square pyramids. The corner-sharing octahedral tilt angles range from 12-62°. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Mn(2) and three equivalent Bi(2) atoms to form a mixture of corner and edge-sharing SeMn2Bi3 square pyramids. In the second Se site, Se(2) is bonded in a distorted rectangular see-saw-like geometry to one Mn(2), one Bi(1), and two equivalent Bi(2) atoms. In the third Se site, Se(3) is bonded to two equivalent Mn(1) and three equivalent Bi(1) atoms to form a mixture of corner and edge-sharing SeMn2Bi3 square pyramids. In the fourth Se site, Se(4) is bonded in a distorted T-shaped geometry to one Mn(1) and two equivalent Bi(1) atoms. is represented by the CIF card [CIF]
data_Mn(BiSe2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.079
_cell_length_b   6.968
_cell_length_c   14.116
_cell_angle_alpha   87.490
_cell_angle_beta   81.693
_cell_angle_gamma   72.981
_symmetry_Int_Tables_number   1
_cell_volume   379.589
_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
  Mn  Mn0  1  0.000  0.500  0.500  1.0
  Mn  Mn1  1  0.000  0.000  0.000  1.0
  Bi  Bi2  1  0.221  0.930  0.628  1.0
  Bi  Bi3  1  0.779  0.070  0.372  1.0
  Bi  Bi4  1  0.352  0.433  0.863  1.0
  Bi  Bi5  1  0.648  0.567  0.137  1.0
  Se  Se6  1  0.657  0.730  0.956  1.0
  Se  Se7  1  0.343  0.270  0.044  1.0
  Se  Se8  1  0.013  0.148  0.826  1.0
  Se  Se9  1  0.987  0.852  0.174  1.0
  Se  Se10  1  0.601  0.245  0.554  1.0
  Se  Se11  1  0.399  0.755  0.446  1.0
  Se  Se12  1  0.834  0.655  0.678  1.0
  Se  Se13  1  0.166  0.345  0.322  1.0
[/CIF]
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