The crystal structure described by SiO2 is High (Orthorhombic) Tridymite-like 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 one O(1), one O(2), one O(3), and one O(4) atom to form 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. There are six inequivalent O sites. In the first O site, O(2) is bonded in a linear geometry to two equivalent Si(1) atoms. In the second O site, O(3) is bonded in a linear geometry to two equivalent Si(1) atoms. In the third O site, O(4) is bonded in a linear geometry to two equivalent Si(1) atoms. In the fourth O site, O(5) is bonded in a linear geometry to two equivalent Si(2) atoms. In the fifth O site, O(6) is bonded in a linear geometry to two equivalent Si(2) atoms. In the sixth O site, O(1) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_SiO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.556
_cell_length_b   9.260
_cell_length_c   9.260
_cell_angle_alpha   61.883
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   647.110
_cell_formula_units_Z   12
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
  O  O0  1  0.501  0.184  0.645  1.0
  O  O1  1  0.499  0.645  0.184  1.0
  O  O2  1  0.999  0.355  0.816  1.0
  O  O3  1  0.001  0.816  0.355  1.0
  O  O4  1  0.499  0.816  0.355  1.0
  O  O5  1  0.501  0.355  0.816  1.0
  O  O6  1  0.001  0.645  0.184  1.0
  O  O7  1  0.999  0.184  0.645  1.0
  O  O8  1  0.500  0.318  0.318  1.0
  O  O9  1  0.000  0.682  0.682  1.0
  O  O10  1  0.500  0.682  0.682  1.0
  O  O11  1  0.000  0.318  0.318  1.0
  O  O12  1  0.750  0.170  0.485  1.0
  O  O13  1  0.250  0.485  0.170  1.0
  O  O14  1  0.750  0.515  0.830  1.0
  O  O15  1  0.250  0.830  0.515  1.0
  O  O16  1  0.500  1.000  0.500  1.0
  O  O17  1  0.500  0.500  0.000  1.0
  O  O18  1  1.000  0.500  0.000  1.0
  O  O19  1  0.000  1.000  0.500  1.0
  O  O20  1  0.750  0.662  0.338  1.0
  O  O21  1  0.250  0.338  0.662  1.0
  O  O22  1  0.500  0.500  0.500  1.0
  O  O23  1  1.000  0.500  0.500  1.0
  Si  Si24  1  0.563  0.168  0.486  1.0
  Si  Si25  1  0.437  0.486  0.168  1.0
  Si  Si26  1  0.937  0.514  0.832  1.0
  Si  Si27  1  0.063  0.832  0.514  1.0
  Si  Si28  1  0.437  0.832  0.514  1.0
  Si  Si29  1  0.563  0.514  0.832  1.0
  Si  Si30  1  0.063  0.486  0.168  1.0
  Si  Si31  1  0.937  0.168  0.486  1.0
  Si  Si32  1  0.563  0.659  0.341  1.0
  Si  Si33  1  0.437  0.341  0.659  1.0
  Si  Si34  1  0.937  0.659  0.341  1.0
  Si  Si35  1  0.063  0.341  0.659  1.0
[/CIF]
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The crystal structure described by SiO2 is High (Orthorhombic) Tridymite-like 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 one O(1), one O(2), one O(3), and one O(4) atom to form 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. There are six inequivalent O sites. In the first O site, O(2) is bonded in a linear geometry to two equivalent Si(1) atoms. In the second O site, O(3) is bonded in a linear geometry to two equivalent Si(1) atoms. In the third O site, O(4) is bonded in a linear geometry to two equivalent Si(1) atoms. In the fourth O site, O(5) is bonded in a linear geometry to two equivalent Si(2) atoms. In the fifth O site, O(6) is bonded in a linear geometry to two equivalent Si(2) atoms. In the sixth O site, O(1) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_SiO2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.556
_cell_length_b   9.260
_cell_length_c   9.260
_cell_angle_alpha   61.883
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   647.110
_cell_formula_units_Z   12
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
  O  O0  1  0.501  0.184  0.645  1.0
  O  O1  1  0.499  0.645  0.184  1.0
  O  O2  1  0.999  0.355  0.816  1.0
  O  O3  1  0.001  0.816  0.355  1.0
  O  O4  1  0.499  0.816  0.355  1.0
  O  O5  1  0.501  0.355  0.816  1.0
  O  O6  1  0.001  0.645  0.184  1.0
  O  O7  1  0.999  0.184  0.645  1.0
  O  O8  1  0.500  0.318  0.318  1.0
  O  O9  1  0.000  0.682  0.682  1.0
  O  O10  1  0.500  0.682  0.682  1.0
  O  O11  1  0.000  0.318  0.318  1.0
  O  O12  1  0.750  0.170  0.485  1.0
  O  O13  1  0.250  0.485  0.170  1.0
  O  O14  1  0.750  0.515  0.830  1.0
  O  O15  1  0.250  0.830  0.515  1.0
  O  O16  1  0.500  1.000  0.500  1.0
  O  O17  1  0.500  0.500  0.000  1.0
  O  O18  1  1.000  0.500  0.000  1.0
  O  O19  1  0.000  1.000  0.500  1.0
  O  O20  1  0.750  0.662  0.338  1.0
  O  O21  1  0.250  0.338  0.662  1.0
  O  O22  1  0.500  0.500  0.500  1.0
  O  O23  1  1.000  0.500  0.500  1.0
  Si  Si24  1  0.563  0.168  0.486  1.0
  Si  Si25  1  0.437  0.486  0.168  1.0
  Si  Si26  1  0.937  0.514  0.832  1.0
  Si  Si27  1  0.063  0.832  0.514  1.0
  Si  Si28  1  0.437  0.832  0.514  1.0
  Si  Si29  1  0.563  0.514  0.832  1.0
  Si  Si30  1  0.063  0.486  0.168  1.0
  Si  Si31  1  0.937  0.168  0.486  1.0
  Si  Si32  1  0.563  0.659  0.341  1.0
  Si  Si33  1  0.437  0.341  0.659  1.0
  Si  Si34  1  0.937  0.659  0.341  1.0
  Si  Si35  1  0.063  0.341  0.659  1.0
[/CIF]
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