The structure described by SiO2 crystallizes in the monoclinic Pm space group. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form distorted corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(5), one O(6), and two equivalent O(1) atoms to form corner-sharing SiO4 tetrahedra. In the third Si site, Si(3) is bonded to one O(5), one O(6), and two equivalent O(2) atoms to form distorted corner-sharing SiO4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form corner-sharing SiO4 tetrahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Si(3) and one Si(4) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(4) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Si(2) and one Si(3) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Si(2) and one Si(3) atom. is represented by the CIF card [CIF]
data_SiO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.659
_cell_length_b   4.946
_cell_length_c   5.389
_cell_angle_alpha   71.378
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   142.961
_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  0.500  0.544  0.461  1.0
  Si  Si1  1  0.000  0.530  0.488  1.0
  Si  Si2  1  0.000  0.958  0.775  1.0
  Si  Si3  1  0.500  0.013  0.971  1.0
  O  O4  1  0.755  0.456  0.358  1.0
  O  O5  1  0.738  0.859  0.899  1.0
  O  O6  1  0.500  0.357  0.784  1.0
  O  O7  1  0.262  0.859  0.899  1.0
  O  O8  1  0.500  0.901  0.301  1.0
  O  O9  1  0.245  0.456  0.358  1.0
  O  O10  1  0.000  0.849  0.515  1.0
  O  O11  1  0.000  0.290  0.775  1.0
[/CIF]
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The structure described by SiO2 crystallizes in the monoclinic Pm space group. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form distorted corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(5), one O(6), and two equivalent O(1) atoms to form corner-sharing SiO4 tetrahedra. In the third Si site, Si(3) is bonded to one O(5), one O(6), and two equivalent O(2) atoms to form distorted corner-sharing SiO4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form corner-sharing SiO4 tetrahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Si(3) and one Si(4) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(4) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(4) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Si(2) and one Si(3) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Si(2) and one Si(3) atom. is represented by the CIF card [CIF]
data_SiO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.659
_cell_length_b   4.946
_cell_length_c   5.389
_cell_angle_alpha   71.378
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   142.961
_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  0.500  0.544  0.461  1.0
  Si  Si1  1  0.000  0.530  0.488  1.0
  Si  Si2  1  0.000  0.958  0.775  1.0
  Si  Si3  1  0.500  0.013  0.971  1.0
  O  O4  1  0.755  0.456  0.358  1.0
  O  O5  1  0.738  0.859  0.899  1.0
  O  O6  1  0.500  0.357  0.784  1.0
  O  O7  1  0.262  0.859  0.899  1.0
  O  O8  1  0.500  0.901  0.301  1.0
  O  O9  1  0.245  0.456  0.358  1.0
  O  O10  1  0.000  0.849  0.515  1.0
  O  O11  1  0.000  0.290  0.775  1.0
[/CIF]
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