The material structure described by Ca3SiBr2 is Caswellsilverite-like structured and crystallizes in the hexagonal P-6m2 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to six equivalent Br(1) atoms to form distorted CaBr6 pentagonal pyramids that share corners with twelve equivalent Ca(2)Si3Br3 octahedra, edges with six equivalent Ca(1)Br6 pentagonal pyramids, and faces with two equivalent Ca(2)Si3Br3 octahedra. The corner-sharing octahedral tilt angles are 43°. In the second Ca site, Ca(2) is bonded to three equivalent Si(1) and three equivalent Br(1) atoms to form CaSi3Br3 octahedra that share corners with six equivalent Ca(2)Si3Br3 octahedra, corners with six equivalent Ca(1)Br6 pentagonal pyramids, edges with six equivalent Ca(2)Si3Br3 octahedra,  a faceface with one Ca(2)Si3Br3 octahedra, and  a faceface with one Ca(1)Br6 pentagonal pyramid. The corner-sharing octahedral tilt angles are 47°. Si(1) is bonded to six equivalent Ca(2) atoms to form distorted SiCa6 pentagonal pyramids that share corners with six equivalent Br(1)Ca6 pentagonal pyramids, edges with six equivalent Si(1)Ca6 pentagonal pyramids, and edges with six equivalent Br(1)Ca6 pentagonal pyramids. Br(1) is bonded to three equivalent Ca(1) and three equivalent Ca(2) atoms to form distorted BrCa6 pentagonal pyramids that share corners with three equivalent Si(1)Ca6 pentagonal pyramids, corners with six equivalent Br(1)Ca6 pentagonal pyramids, edges with three equivalent Si(1)Ca6 pentagonal pyramids, edges with six equivalent Br(1)Ca6 pentagonal pyramids, and  a faceface with one Br(1)Ca6 pentagonal pyramid. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca3SiBr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.076
_cell_length_b   4.076
_cell_length_c   12.204
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   175.624
_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  0.000  0.000  0.000  1.0
  Ca  Ca1  1  0.000  0.000  0.646  1.0
  Ca  Ca2  1  0.000  0.000  0.354  1.0
  Si  Si3  1  0.667  0.333  0.500  1.0
  Br  Br4  1  0.333  0.667  0.828  1.0
  Br  Br5  1  0.333  0.667  0.172  1.0
[/CIF]
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The material structure described by Ca3SiBr2 is Caswellsilverite-like structured and crystallizes in the hexagonal P-6m2 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to six equivalent Br(1) atoms to form distorted CaBr6 pentagonal pyramids that share corners with twelve equivalent Ca(2)Si3Br3 octahedra, edges with six equivalent Ca(1)Br6 pentagonal pyramids, and faces with two equivalent Ca(2)Si3Br3 octahedra. The corner-sharing octahedral tilt angles are 43°. In the second Ca site, Ca(2) is bonded to three equivalent Si(1) and three equivalent Br(1) atoms to form CaSi3Br3 octahedra that share corners with six equivalent Ca(2)Si3Br3 octahedra, corners with six equivalent Ca(1)Br6 pentagonal pyramids, edges with six equivalent Ca(2)Si3Br3 octahedra,  a faceface with one Ca(2)Si3Br3 octahedra, and  a faceface with one Ca(1)Br6 pentagonal pyramid. The corner-sharing octahedral tilt angles are 47°. Si(1) is bonded to six equivalent Ca(2) atoms to form distorted SiCa6 pentagonal pyramids that share corners with six equivalent Br(1)Ca6 pentagonal pyramids, edges with six equivalent Si(1)Ca6 pentagonal pyramids, and edges with six equivalent Br(1)Ca6 pentagonal pyramids. Br(1) is bonded to three equivalent Ca(1) and three equivalent Ca(2) atoms to form distorted BrCa6 pentagonal pyramids that share corners with three equivalent Si(1)Ca6 pentagonal pyramids, corners with six equivalent Br(1)Ca6 pentagonal pyramids, edges with three equivalent Si(1)Ca6 pentagonal pyramids, edges with six equivalent Br(1)Ca6 pentagonal pyramids, and  a faceface with one Br(1)Ca6 pentagonal pyramid. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca3SiBr2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.076
_cell_length_b   4.076
_cell_length_c   12.204
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   175.624
_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  0.000  0.000  0.000  1.0
  Ca  Ca1  1  0.000  0.000  0.646  1.0
  Ca  Ca2  1  0.000  0.000  0.354  1.0
  Si  Si3  1  0.667  0.333  0.500  1.0
  Br  Br4  1  0.333  0.667  0.828  1.0
  Br  Br5  1  0.333  0.667  0.172  1.0
[/CIF]
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