The compound described by Si is BC8 structured and crystallizes in the trigonal R-3 space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one Si(2) and three equivalent Si(1) atoms to form corner-sharing SiSi4 trigonal pyramids. In the second Si site, Si(2) is bonded to one Si(2) and three equivalent Si(1) atoms to form corner-sharing SiSi4 trigonal pyramids. is represented by the CIF file [CIF]
data_Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.759
_cell_length_b   5.759
_cell_length_c   5.759
_cell_angle_alpha   109.845
_cell_angle_beta   109.845
_cell_angle_gamma   109.845
_symmetry_Int_Tables_number   1
_cell_volume   144.980
_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
  Si  Si0  1  0.017  0.715  0.519  1.0
  Si  Si1  1  0.983  0.285  0.481  1.0
  Si  Si2  1  0.713  0.713  0.713  1.0
  Si  Si3  1  0.285  0.481  0.983  1.0
  Si  Si4  1  0.481  0.983  0.285  1.0
  Si  Si5  1  0.715  0.519  0.017  1.0
  Si  Si6  1  0.287  0.287  0.287  1.0
  Si  Si7  1  0.519  0.017  0.715  1.0
[/CIF]
.
The compound described by Si is BC8 structured and crystallizes in the trigonal R-3 space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one Si(2) and three equivalent Si(1) atoms to form corner-sharing SiSi4 trigonal pyramids. In the second Si site, Si(2) is bonded to one Si(2) and three equivalent Si(1) atoms to form corner-sharing SiSi4 trigonal pyramids. is represented by the CIF file [CIF]
data_Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.759
_cell_length_b   5.759
_cell_length_c   5.759
_cell_angle_alpha   109.845
_cell_angle_beta   109.845
_cell_angle_gamma   109.845
_symmetry_Int_Tables_number   1
_cell_volume   144.980
_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
  Si  Si0  1  0.017  0.715  0.519  1.0
  Si  Si1  1  0.983  0.285  0.481  1.0
  Si  Si2  1  0.713  0.713  0.713  1.0
  Si  Si3  1  0.285  0.481  0.983  1.0
  Si  Si4  1  0.481  0.983  0.285  1.0
  Si  Si5  1  0.715  0.519  0.017  1.0
  Si  Si6  1  0.287  0.287  0.287  1.0
  Si  Si7  1  0.519  0.017  0.715  1.0
[/CIF]
.