The material structure described by Ca3SiBr2 crystallizes in the trigonal R3m space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent Br(1) and three equivalent Br(2) atoms to form CaBr6 octahedra that share corners with three equivalent Ca(3)Si3Br3 octahedra, edges with three equivalent Ca(3)Si3Br3 octahedra, and edges with six equivalent Ca(1)Br6 octahedra. The corner-sharing octahedral tilt angles are 11°. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to three equivalent Si(1) and three equivalent Br(2) atoms. In the third Ca site, Ca(3) is bonded to three equivalent Si(1) and three equivalent Br(1) atoms to form distorted CaSi3Br3 octahedra that share corners with three equivalent Ca(1)Br6 octahedra, edges with three equivalent Ca(1)Br6 octahedra, and edges with six equivalent Ca(3)Si3Br3 octahedra. The corner-sharing octahedral tilt angles are 11°. Si(1) is bonded in a 6-coordinate geometry to three equivalent Ca(2) and three equivalent Ca(3) atoms. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded to three equivalent Ca(1) and three equivalent Ca(3) atoms to form edge-sharing BrCa6 octahedra. In the second Br site, Br(2) is bonded in a 6-coordinate geometry to three equivalent Ca(1) and three equivalent Ca(2) atoms. is represented by the CIF file [CIF]
data_Ca3SiBr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.985
_cell_length_b   11.985
_cell_length_c   11.985
_cell_angle_alpha   20.594
_cell_angle_beta   20.594
_cell_angle_gamma   20.594
_symmetry_Int_Tables_number   1
_cell_volume   186.457
_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
  Ca  Ca0  1  0.119  0.119  0.119  1.0
  Ca  Ca1  1  0.996  0.996  0.996  1.0
  Ca  Ca2  1  0.905  0.905  0.905  1.0
  Si  Si3  1  0.284  0.284  0.284  1.0
  Br  Br4  1  0.500  0.500  0.500  1.0
  Br  Br5  1  0.739  0.739  0.739  1.0
[/CIF]
.
The material structure described by Ca3SiBr2 crystallizes in the trigonal R3m space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent Br(1) and three equivalent Br(2) atoms to form CaBr6 octahedra that share corners with three equivalent Ca(3)Si3Br3 octahedra, edges with three equivalent Ca(3)Si3Br3 octahedra, and edges with six equivalent Ca(1)Br6 octahedra. The corner-sharing octahedral tilt angles are 11°. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to three equivalent Si(1) and three equivalent Br(2) atoms. In the third Ca site, Ca(3) is bonded to three equivalent Si(1) and three equivalent Br(1) atoms to form distorted CaSi3Br3 octahedra that share corners with three equivalent Ca(1)Br6 octahedra, edges with three equivalent Ca(1)Br6 octahedra, and edges with six equivalent Ca(3)Si3Br3 octahedra. The corner-sharing octahedral tilt angles are 11°. Si(1) is bonded in a 6-coordinate geometry to three equivalent Ca(2) and three equivalent Ca(3) atoms. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded to three equivalent Ca(1) and three equivalent Ca(3) atoms to form edge-sharing BrCa6 octahedra. In the second Br site, Br(2) is bonded in a 6-coordinate geometry to three equivalent Ca(1) and three equivalent Ca(2) atoms. is represented by the CIF file [CIF]
data_Ca3SiBr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.985
_cell_length_b   11.985
_cell_length_c   11.985
_cell_angle_alpha   20.594
_cell_angle_beta   20.594
_cell_angle_gamma   20.594
_symmetry_Int_Tables_number   1
_cell_volume   186.457
_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
  Ca  Ca0  1  0.119  0.119  0.119  1.0
  Ca  Ca1  1  0.996  0.996  0.996  1.0
  Ca  Ca2  1  0.905  0.905  0.905  1.0
  Si  Si3  1  0.284  0.284  0.284  1.0
  Br  Br4  1  0.500  0.500  0.500  1.0
  Br  Br5  1  0.739  0.739  0.739  1.0
[/CIF]
.