SiO2 is High (Orthorhombic) Tridymite-like structured and crystallizes in the orthorhombic Cmcm space group. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(5), and two equivalent O(4) atoms to form corner-sharing SiO4 tetrahedra. In the third Si site, Si(3) is bonded to one O(3), one O(6), and two equivalent O(4) atoms to form corner-sharing SiO4 tetrahedra. There are six inequivalent O sites. In the first O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the second O site, O(4) is bonded in a linear geometry to one Si(2) and one Si(3) atom. In the third O site, O(5) is bonded in a linear geometry to two equivalent Si(2) atoms. In the fourth O site, O(6) is bonded in a linear geometry to two equivalent Si(3) atoms. In the fifth O site, O(1) is bonded in a linear geometry to one Si(1) and one Si(2) atom. In the sixth O site, O(2) is bonded in a linear geometry to two equivalent Si(1) atoms.
SiO2 is High (Orthorhombic) Tridymite-like structured and crystallizes in the orthorhombic Cmcm space group. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form corner-sharing SiO4 tetrahedra. The Si(1)-O(1) bond length is 1.60 Å. The Si(1)-O(3) bond length is 1.61 Å. Both Si(1)-O(2) bond lengths are 1.61 Å. In the second Si site, Si(2) is bonded to one O(1), one O(5), and two equivalent O(4) atoms to form corner-sharing SiO4 tetrahedra. The Si(2)-O(1) bond length is 1.61 Å. The Si(2)-O(5) bond length is 1.60 Å. Both Si(2)-O(4) bond lengths are 1.60 Å. In the third Si site, Si(3) is bonded to one O(3), one O(6), and two equivalent O(4) atoms to form corner-sharing SiO4 tetrahedra. The Si(3)-O(3) bond length is 1.61 Å. The Si(3)-O(6) bond length is 1.61 Å. Both Si(3)-O(4) bond lengths are 1.60 Å. There are six inequivalent O sites. In the first O site, O(3) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the second O site, O(4) is bonded in a linear geometry to one Si(2) and one Si(3) atom. In the third O site, O(5) is bonded in a linear geometry to two equivalent Si(2) atoms. In the fourth O site, O(6) is bonded in a linear geometry to two equivalent Si(3) atoms. In the fifth O site, O(1) is bonded in a linear geometry to one Si(1) and one Si(2) atom. In the sixth O site, O(2) is bonded in a linear geometry to two equivalent Si(1) atoms.