The material structure described by Si crystallizes in the triclinic P1 space group. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted pentagonal planar geometry to one Si(3), one Si(4), one Si(7), and two equivalent Si(5) atoms. In the second Si site, Si(2) is bonded in a 4-coordinate geometry to one Si(4), one Si(6), one Si(7), and one Si(8) atom. In the third Si site, Si(3) is bonded in a tetrahedral geometry to one Si(1), one Si(5), one Si(6), and one Si(7) atom. In the fourth Si site, Si(4) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), one Si(6), and one Si(8) atom. In the fifth Si site, Si(5) is bonded in a 4-coordinate geometry to one Si(3), one Si(8), and two equivalent Si(1) atoms. In the sixth Si site, Si(6) is bonded in a 5-coordinate geometry to one Si(2), one Si(3), one Si(4), one Si(7), and one Si(8) atom. In the seventh Si site, Si(7) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(3), one Si(6), and one Si(8) atom. In the eighth Si site, Si(8) is bonded in a 5-coordinate geometry to one Si(2), one Si(4), one Si(5), one Si(6), and one Si(7) atom. is represented by the CIF file [CIF]
data_Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.935
_cell_length_b   5.392
_cell_length_c   7.137
_cell_angle_alpha   92.412
_cell_angle_beta   109.811
_cell_angle_gamma   114.308
_symmetry_Int_Tables_number   1
_cell_volume   159.131
_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  0.713  0.048  0.841  1.0
  Si  Si1  1  0.590  0.100  0.255  1.0
  Si  Si2  1  0.462  0.580  0.674  1.0
  Si  Si3  1  0.174  0.268  0.147  1.0
  Si  Si4  1  0.234  0.141  0.760  1.0
  Si  Si5  1  0.079  0.554  0.356  1.0
  Si  Si6  1  0.729  0.335  0.594  1.0
  Si  Si7  1  0.075  0.990  0.395  1.0
[/CIF]
.
The material structure described by Si crystallizes in the triclinic P1 space group. There are eight inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted pentagonal planar geometry to one Si(3), one Si(4), one Si(7), and two equivalent Si(5) atoms. In the second Si site, Si(2) is bonded in a 4-coordinate geometry to one Si(4), one Si(6), one Si(7), and one Si(8) atom. In the third Si site, Si(3) is bonded in a tetrahedral geometry to one Si(1), one Si(5), one Si(6), and one Si(7) atom. In the fourth Si site, Si(4) is bonded in a 4-coordinate geometry to one Si(1), one Si(2), one Si(6), and one Si(8) atom. In the fifth Si site, Si(5) is bonded in a 4-coordinate geometry to one Si(3), one Si(8), and two equivalent Si(1) atoms. In the sixth Si site, Si(6) is bonded in a 5-coordinate geometry to one Si(2), one Si(3), one Si(4), one Si(7), and one Si(8) atom. In the seventh Si site, Si(7) is bonded in a 5-coordinate geometry to one Si(1), one Si(2), one Si(3), one Si(6), and one Si(8) atom. In the eighth Si site, Si(8) is bonded in a 5-coordinate geometry to one Si(2), one Si(4), one Si(5), one Si(6), and one Si(7) atom. is represented by the CIF file [CIF]
data_Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.935
_cell_length_b   5.392
_cell_length_c   7.137
_cell_angle_alpha   92.412
_cell_angle_beta   109.811
_cell_angle_gamma   114.308
_symmetry_Int_Tables_number   1
_cell_volume   159.131
_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  0.713  0.048  0.841  1.0
  Si  Si1  1  0.590  0.100  0.255  1.0
  Si  Si2  1  0.462  0.580  0.674  1.0
  Si  Si3  1  0.174  0.268  0.147  1.0
  Si  Si4  1  0.234  0.141  0.760  1.0
  Si  Si5  1  0.079  0.554  0.356  1.0
  Si  Si6  1  0.729  0.335  0.594  1.0
  Si  Si7  1  0.075  0.990  0.395  1.0
[/CIF]
.