The crystal structure described by Si is black P structured and crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent Si(1) and five equivalent Si(2) atoms to form distorted SiSi7 pentagonal bipyramids that share corners with four equivalent Si(1)Si7 pentagonal bipyramids, corners with six equivalent Si(2)Si5 trigonal bipyramids, edges with six equivalent Si(1)Si7 pentagonal bipyramids, edges with two equivalent Si(2)Si5 trigonal bipyramids, and faces with two equivalent Si(1)Si7 pentagonal bipyramids. In the second Si site, Si(2) is bonded to five equivalent Si(1) atoms to form distorted SiSi5 trigonal bipyramids that share corners with six equivalent Si(1)Si7 pentagonal bipyramids, corners with four equivalent Si(2)Si5 trigonal bipyramids, edges with two equivalent Si(1)Si7 pentagonal bipyramids, and edges with eight equivalent Si(2)Si5 trigonal bipyramids. is represented by the CIF file [CIF]
data_Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.469
_cell_length_b   5.469
_cell_length_c   3.478
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   143.249
_symmetry_Int_Tables_number   1
_cell_volume   62.231
_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
  Si  Si0  1  0.906  0.094  0.750  1.0
  Si  Si1  1  0.665  0.335  0.750  1.0
  Si  Si2  1  0.094  0.906  0.250  1.0
  Si  Si3  1  0.335  0.665  0.250  1.0
[/CIF]
.
The crystal structure described by Si is black P structured and crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent Si(1) and five equivalent Si(2) atoms to form distorted SiSi7 pentagonal bipyramids that share corners with four equivalent Si(1)Si7 pentagonal bipyramids, corners with six equivalent Si(2)Si5 trigonal bipyramids, edges with six equivalent Si(1)Si7 pentagonal bipyramids, edges with two equivalent Si(2)Si5 trigonal bipyramids, and faces with two equivalent Si(1)Si7 pentagonal bipyramids. In the second Si site, Si(2) is bonded to five equivalent Si(1) atoms to form distorted SiSi5 trigonal bipyramids that share corners with six equivalent Si(1)Si7 pentagonal bipyramids, corners with four equivalent Si(2)Si5 trigonal bipyramids, edges with two equivalent Si(1)Si7 pentagonal bipyramids, and edges with eight equivalent Si(2)Si5 trigonal bipyramids. is represented by the CIF file [CIF]
data_Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.469
_cell_length_b   5.469
_cell_length_c   3.478
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   143.249
_symmetry_Int_Tables_number   1
_cell_volume   62.231
_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
  Si  Si0  1  0.906  0.094  0.750  1.0
  Si  Si1  1  0.665  0.335  0.750  1.0
  Si  Si2  1  0.094  0.906  0.250  1.0
  Si  Si3  1  0.335  0.665  0.250  1.0
[/CIF]
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