The crystal structure described by Si is Theoretical Carbon Structure-like structured and crystallizes in the cubic I-43m space group. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one Si(4) and three equivalent Si(1) atoms to form a mixture of edge and corner-sharing SiSi4 tetrahedra. In the second Si site, Si(2) is bonded to one Si(3) and three equivalent Si(4) atoms to form corner-sharing SiSi4 tetrahedra. In the third Si site, Si(3) is bonded to four equivalent Si(2) atoms to form corner-sharing SiSi4 tetrahedra. In the fourth Si site, Si(4) is bonded to one Si(2), one Si(4), and two equivalent Si(1) atoms to form corner-sharing SiSi4 tetrahedra. is represented by the CIF file [CIF]
data_Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.763
_cell_length_b   10.763
_cell_length_c   10.763
_cell_angle_alpha   109.471
_cell_angle_beta   109.471
_cell_angle_gamma   109.471
_symmetry_Int_Tables_number   1
_cell_volume   959.872
_cell_formula_units_Z   41
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  0.787  0.392  0.133  1.0
  Si  Si1  1  0.395  0.741  0.608  1.0
  Si  Si2  1  0.654  0.867  0.259  1.0
  Si  Si3  1  0.654  0.259  0.867  1.0
  Si  Si4  1  0.787  0.133  0.392  1.0
  Si  Si5  1  0.395  0.608  0.741  1.0
  Si  Si6  1  0.259  0.654  0.867  1.0
  Si  Si7  1  0.133  0.787  0.392  1.0
  Si  Si8  1  0.608  0.395  0.741  1.0
  Si  Si9  1  0.392  0.787  0.133  1.0
  Si  Si10  1  0.741  0.395  0.608  1.0
  Si  Si11  1  0.867  0.654  0.259  1.0
  Si  Si12  1  0.741  0.608  0.395  1.0
  Si  Si13  1  0.867  0.259  0.654  1.0
  Si  Si14  1  0.392  0.133  0.787  1.0
  Si  Si15  1  0.608  0.741  0.395  1.0
  Si  Si16  1  0.259  0.867  0.654  1.0
  Si  Si17  1  0.133  0.392  0.787  1.0
  Si  Si18  1  0.213  0.346  0.605  1.0
  Si  Si19  1  0.605  0.213  0.346  1.0
  Si  Si20  1  0.346  0.605  0.213  1.0
  Si  Si21  1  0.346  0.213  0.605  1.0
  Si  Si22  1  0.213  0.605  0.346  1.0
  Si  Si23  1  0.605  0.346  0.213  1.0
  Si  Si24  1  0.000  0.000  0.217  1.0
  Si  Si25  1  0.000  0.217  0.000  1.0
  Si  Si26  1  0.783  0.783  0.783  1.0
  Si  Si27  1  0.217  0.000  0.000  1.0
  Si  Si28  1  0.000  0.000  0.000  1.0
  Si  Si29  1  0.000  0.359  0.224  1.0
  Si  Si30  1  0.641  0.864  0.641  1.0
  Si  Si31  1  0.776  0.776  0.136  1.0
  Si  Si32  1  0.776  0.136  0.776  1.0
  Si  Si33  1  0.000  0.224  0.359  1.0
  Si  Si34  1  0.641  0.641  0.864  1.0
  Si  Si35  1  0.136  0.776  0.776  1.0
  Si  Si36  1  0.224  0.000  0.359  1.0
  Si  Si37  1  0.359  0.000  0.224  1.0
  Si  Si38  1  0.864  0.641  0.641  1.0
  Si  Si39  1  0.359  0.224  0.000  1.0
  Si  Si40  1  0.224  0.359  0.000  1.0
[/CIF]
.
The crystal structure described by Si is Theoretical Carbon Structure-like structured and crystallizes in the cubic I-43m space group. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one Si(4) and three equivalent Si(1) atoms to form a mixture of edge and corner-sharing SiSi4 tetrahedra. In the second Si site, Si(2) is bonded to one Si(3) and three equivalent Si(4) atoms to form corner-sharing SiSi4 tetrahedra. In the third Si site, Si(3) is bonded to four equivalent Si(2) atoms to form corner-sharing SiSi4 tetrahedra. In the fourth Si site, Si(4) is bonded to one Si(2), one Si(4), and two equivalent Si(1) atoms to form corner-sharing SiSi4 tetrahedra. is represented by the CIF file [CIF]
data_Si
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.763
_cell_length_b   10.763
_cell_length_c   10.763
_cell_angle_alpha   109.471
_cell_angle_beta   109.471
_cell_angle_gamma   109.471
_symmetry_Int_Tables_number   1
_cell_volume   959.872
_cell_formula_units_Z   41
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  0.787  0.392  0.133  1.0
  Si  Si1  1  0.395  0.741  0.608  1.0
  Si  Si2  1  0.654  0.867  0.259  1.0
  Si  Si3  1  0.654  0.259  0.867  1.0
  Si  Si4  1  0.787  0.133  0.392  1.0
  Si  Si5  1  0.395  0.608  0.741  1.0
  Si  Si6  1  0.259  0.654  0.867  1.0
  Si  Si7  1  0.133  0.787  0.392  1.0
  Si  Si8  1  0.608  0.395  0.741  1.0
  Si  Si9  1  0.392  0.787  0.133  1.0
  Si  Si10  1  0.741  0.395  0.608  1.0
  Si  Si11  1  0.867  0.654  0.259  1.0
  Si  Si12  1  0.741  0.608  0.395  1.0
  Si  Si13  1  0.867  0.259  0.654  1.0
  Si  Si14  1  0.392  0.133  0.787  1.0
  Si  Si15  1  0.608  0.741  0.395  1.0
  Si  Si16  1  0.259  0.867  0.654  1.0
  Si  Si17  1  0.133  0.392  0.787  1.0
  Si  Si18  1  0.213  0.346  0.605  1.0
  Si  Si19  1  0.605  0.213  0.346  1.0
  Si  Si20  1  0.346  0.605  0.213  1.0
  Si  Si21  1  0.346  0.213  0.605  1.0
  Si  Si22  1  0.213  0.605  0.346  1.0
  Si  Si23  1  0.605  0.346  0.213  1.0
  Si  Si24  1  0.000  0.000  0.217  1.0
  Si  Si25  1  0.000  0.217  0.000  1.0
  Si  Si26  1  0.783  0.783  0.783  1.0
  Si  Si27  1  0.217  0.000  0.000  1.0
  Si  Si28  1  0.000  0.000  0.000  1.0
  Si  Si29  1  0.000  0.359  0.224  1.0
  Si  Si30  1  0.641  0.864  0.641  1.0
  Si  Si31  1  0.776  0.776  0.136  1.0
  Si  Si32  1  0.776  0.136  0.776  1.0
  Si  Si33  1  0.000  0.224  0.359  1.0
  Si  Si34  1  0.641  0.641  0.864  1.0
  Si  Si35  1  0.136  0.776  0.776  1.0
  Si  Si36  1  0.224  0.000  0.359  1.0
  Si  Si37  1  0.359  0.000  0.224  1.0
  Si  Si38  1  0.864  0.641  0.641  1.0
  Si  Si39  1  0.359  0.224  0.000  1.0
  Si  Si40  1  0.224  0.359  0.000  1.0
[/CIF]
.