The compound described by SiO2 is Low Tridymite-like structured and crystallizes in the hexagonal P-6m2 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(3) atoms to form corner-sharing SiO4 tetrahedra. There are six inequivalent O sites. In the first O site, O(4) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(5) is bonded in a bent 150 degrees geometry to two equivalent Si(2) atoms. In the third O site, O(1) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the fourth O site, O(6) is bonded in a linear geometry to two equivalent Si(2) atoms. In the fifth O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the sixth O site, O(3) is bonded in a bent 150 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   13.034
_cell_length_b   13.034
_cell_length_c   7.597
_cell_angle_alpha   89.999
_cell_angle_beta   90.000
_cell_angle_gamma   119.999
_symmetry_Int_Tables_number   1
_cell_volume   1117.737
_cell_formula_units_Z   18
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  0.995  0.228  0.193  1.0
  Si  Si1  1  0.757  0.752  0.193  1.0
  Si  Si2  1  0.233  0.990  0.193  1.0
  Si  Si3  1  0.995  0.228  0.787  1.0
  Si  Si4  1  0.757  0.752  0.787  1.0
  Si  Si5  1  0.233  0.990  0.787  1.0
  Si  Si6  1  0.757  0.990  0.193  1.0
  Si  Si7  1  0.233  0.228  0.193  1.0
  Si  Si8  1  0.995  0.752  0.193  1.0
  Si  Si9  1  0.757  0.990  0.787  1.0
  Si  Si10  1  0.233  0.228  0.787  1.0
  Si  Si11  1  0.995  0.752  0.787  1.0
  Si  Si12  1  0.086  0.414  0.490  1.0
  Si  Si13  1  0.572  0.658  0.490  1.0
  Si  Si14  1  0.327  0.899  0.490  1.0
  Si  Si15  1  0.572  0.899  0.490  1.0
  Si  Si16  1  0.327  0.414  0.490  1.0
  Si  Si17  1  0.086  0.658  0.490  1.0
  O  O18  1  0.097  0.193  0.222  1.0
  O  O19  1  0.792  0.889  0.222  1.0
  O  O20  1  0.097  0.889  0.222  1.0
  O  O21  1  0.097  0.193  0.757  1.0
  O  O22  1  0.792  0.889  0.757  1.0
  O  O23  1  0.097  0.889  0.757  1.0
  O  O24  1  0.869  0.116  0.244  1.0
  O  O25  1  0.869  0.738  0.244  1.0
  O  O26  1  0.247  0.116  0.244  1.0
  O  O27  1  0.869  0.116  0.736  1.0
  O  O28  1  0.869  0.738  0.736  1.0
  O  O29  1  0.247  0.116  0.736  1.0
  O  O30  1  0.020  0.339  0.316  1.0
  O  O31  1  0.647  0.667  0.316  1.0
  O  O32  1  0.319  0.965  0.316  1.0
  O  O33  1  0.020  0.339  0.664  1.0
  O  O34  1  0.647  0.667  0.664  1.0
  O  O35  1  0.319  0.965  0.664  1.0
  O  O36  1  0.647  0.965  0.316  1.0
  O  O37  1  0.318  0.339  0.316  1.0
  O  O38  1  0.020  0.667  0.316  1.0
  O  O39  1  0.647  0.965  0.664  1.0
  O  O40  1  0.319  0.339  0.664  1.0
  O  O41  1  0.020  0.667  0.664  1.0
  O  O42  1  0.995  0.265  0.990  1.0
  O  O43  1  0.720  0.715  0.990  1.0
  O  O44  1  0.270  0.990  0.990  1.0
  O  O45  1  0.720  0.990  0.990  1.0
  O  O46  1  0.270  0.265  0.990  1.0
  O  O47  1  0.995  0.715  0.990  1.0
  O  O48  1  0.223  0.445  0.490  1.0
  O  O49  1  0.540  0.763  0.490  1.0
  O  O50  1  0.223  0.763  0.490  1.0
  O  O51  1  0.081  0.533  0.490  1.0
  O  O52  1  0.452  0.533  0.490  1.0
  O  O53  1  0.452  0.905  0.490  1.0
[/CIF]
.
The compound described by SiO2 is Low Tridymite-like structured and crystallizes in the hexagonal P-6m2 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(3) atoms to form corner-sharing SiO4 tetrahedra. There are six inequivalent O sites. In the first O site, O(4) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(5) is bonded in a bent 150 degrees geometry to two equivalent Si(2) atoms. In the third O site, O(1) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the fourth O site, O(6) is bonded in a linear geometry to two equivalent Si(2) atoms. In the fifth O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the sixth O site, O(3) is bonded in a bent 150 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   13.034
_cell_length_b   13.034
_cell_length_c   7.597
_cell_angle_alpha   89.999
_cell_angle_beta   90.000
_cell_angle_gamma   119.999
_symmetry_Int_Tables_number   1
_cell_volume   1117.737
_cell_formula_units_Z   18
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  0.995  0.228  0.193  1.0
  Si  Si1  1  0.757  0.752  0.193  1.0
  Si  Si2  1  0.233  0.990  0.193  1.0
  Si  Si3  1  0.995  0.228  0.787  1.0
  Si  Si4  1  0.757  0.752  0.787  1.0
  Si  Si5  1  0.233  0.990  0.787  1.0
  Si  Si6  1  0.757  0.990  0.193  1.0
  Si  Si7  1  0.233  0.228  0.193  1.0
  Si  Si8  1  0.995  0.752  0.193  1.0
  Si  Si9  1  0.757  0.990  0.787  1.0
  Si  Si10  1  0.233  0.228  0.787  1.0
  Si  Si11  1  0.995  0.752  0.787  1.0
  Si  Si12  1  0.086  0.414  0.490  1.0
  Si  Si13  1  0.572  0.658  0.490  1.0
  Si  Si14  1  0.327  0.899  0.490  1.0
  Si  Si15  1  0.572  0.899  0.490  1.0
  Si  Si16  1  0.327  0.414  0.490  1.0
  Si  Si17  1  0.086  0.658  0.490  1.0
  O  O18  1  0.097  0.193  0.222  1.0
  O  O19  1  0.792  0.889  0.222  1.0
  O  O20  1  0.097  0.889  0.222  1.0
  O  O21  1  0.097  0.193  0.757  1.0
  O  O22  1  0.792  0.889  0.757  1.0
  O  O23  1  0.097  0.889  0.757  1.0
  O  O24  1  0.869  0.116  0.244  1.0
  O  O25  1  0.869  0.738  0.244  1.0
  O  O26  1  0.247  0.116  0.244  1.0
  O  O27  1  0.869  0.116  0.736  1.0
  O  O28  1  0.869  0.738  0.736  1.0
  O  O29  1  0.247  0.116  0.736  1.0
  O  O30  1  0.020  0.339  0.316  1.0
  O  O31  1  0.647  0.667  0.316  1.0
  O  O32  1  0.319  0.965  0.316  1.0
  O  O33  1  0.020  0.339  0.664  1.0
  O  O34  1  0.647  0.667  0.664  1.0
  O  O35  1  0.319  0.965  0.664  1.0
  O  O36  1  0.647  0.965  0.316  1.0
  O  O37  1  0.318  0.339  0.316  1.0
  O  O38  1  0.020  0.667  0.316  1.0
  O  O39  1  0.647  0.965  0.664  1.0
  O  O40  1  0.319  0.339  0.664  1.0
  O  O41  1  0.020  0.667  0.664  1.0
  O  O42  1  0.995  0.265  0.990  1.0
  O  O43  1  0.720  0.715  0.990  1.0
  O  O44  1  0.270  0.990  0.990  1.0
  O  O45  1  0.720  0.990  0.990  1.0
  O  O46  1  0.270  0.265  0.990  1.0
  O  O47  1  0.995  0.715  0.990  1.0
  O  O48  1  0.223  0.445  0.490  1.0
  O  O49  1  0.540  0.763  0.490  1.0
  O  O50  1  0.223  0.763  0.490  1.0
  O  O51  1  0.081  0.533  0.490  1.0
  O  O52  1  0.452  0.533  0.490  1.0
  O  O53  1  0.452  0.905  0.490  1.0
[/CIF]
.